The Magpies started the game slowly and the Saints made them pay, taking the lead after just 10 minutes through centre-back Jan Bednarek.
The fact I have mentioned his position is worth noting because Southampton's attackers, save for Matheus Fernandes, who took his late finish well before it got ruled out for offside, lacked an edge in front of goal.
At the other end of the pitch, Newcastle's Alexander Isak netted his 16th and 17th Premier League goals of the 2024-25 campaign.
The Swedish striker won a penalty soon after Newcastle went behind, and this goal acted as a catalyst for his team.
Isak curled beyond Alex McCarthy just four minutes later and, after half-time, Sandro Tonali finished with similar confidence.
Newcastle's win means they have won six away from home in the Premier League this term, the same amount they managed in the entirety of 2023-24.
For Southampton, the loss against the Magpies was the first time in their league history that they have been beaten in six consecutive home matches.
Southampton 1-3 Newcastle - send us your thoughtspublished at 17:01 25 January
Sutton's predictions: Southampton v Newcastlepublished at 11:19 25 January
11:19 25 January
All the talk before Newcastle played Bournemouth was whether Eddie Howe's side could push Liverpool in the title race, but that talk has stopped since they lost 4-1.
They are still right in the mix for a top-four finish, but it is important for them to quickly get back to winning ways - and this seems like a good game for them to do that.
Southampton have made a decent fist of it in their past two games, against Manchester United and Nottingham Forest, but they still ended up losing both of them.
Let's face it, they are as good as down. Their situation is so bad that, when we spoke about the relegation battle on this week's Monday Night Club, we didn't even mention them - the assumption is that they are already gone.
Their main aim now is to avoid going down with the lowest points tally in Premier League history.
They have got 16 games left to pick up the six points that would see them beat Derby County's tally of 11 points from 2007-08.
It is a big incentive because Robbie Savage, who was Derby's captain that season, has had to live with that record for years.
I'd really like him to keep hold of it, so let's all pray for Southampton to reach the 12-point mark. I don't see them picking anything up here though.
Howe on 'ultimate professional' Almiron and Pope's returnpublished at 10:22 24 January
10:22 24 January
Tyrese King BBC Sport journalist
Newcastle United boss Eddie Howe has been speaking to the media before Saturday's Premier League game against Southampton (kick-off 15:00 GMT).
Here are the key lines from his news conference:
On Miguel Almiron leaving this transfer window: "I think Miggy's head has been very solidly here. He's been brilliant in training and I never thought for one moment that I had to have a deeper conversation with him [about this]. We are both aware that other clubs have shown interest in him."
Howe also added: "We love him to bits, he's got a great energy and character that's never changed for a second - he's been the ultimate professional. And let's see what happens."
Howe believes there needs to be a "response" from Newcastle after losing their last game, stating: "We need to learn from Bournemouth, we need a response. I have no doubt the players will respond. We will go to Southampton absolutely focused. Southampton are a proud football club, and we will have to be at our absolute best."
On Southampton: "I take that they're more mixed now, I'd say that there are still elements of that possession-based play in their game. I don't think that will go away quickly because they've been playing that way for a long period of time, the new manager is obviously embracing that as well."
Southampton have become "very aggressive" off the ball and adopted a "man-for-man style" according to Howe.
On Nick Pope being available for selection: "There's a chance he'll be in the squad. He's started training with the group again and it's great to see Nick back and his presence, his positivity that he brings. I've seen him do some really good things this week, so yes, delighted to have him back in the mix."
Howe says it is "too early" for striker Callum Wilson despite the "good progress" made to start straining with the group.
Efficient or ineffective?published at 08:05 24 January
08:05 24 January
This Premier League pursuit becomes a lot easier if you take your chances.
BBC Sport has checked in on some data comparing goals versus expected goals this season.
You can see from the bar graph some teams aren't finding the goals (yellow) to outstrip the expected goals they should score (black).
Tottenham, Manchester City, Arsenal, Brentford, Newcastle, Brighton, Fulham, Nottingham Forest, Wolves and Leicester have all scored more than expected.
Wolves in particular have found the net 32 times from an expected 23.56 - a significant overperformance.
League leaders Liverpool are pretty much bang on in returning what they should, while Arsenal have outperformed, with 43 goals from an expected 37.78.
Bournemouth - 36 goals from an expected 43 - are leaving opportunities on the table.
Southampton v Newcastle: Did you know?published at 10:56 23 January
10:56 23 January
Image source, Getty Images
Newcastle have lost just one of their past 23 Premier League games against promoted sides, going down 1-0 at Luton in December 2023. Since that defeat at Kenilworth Road, the Magpies have scored at least four goals in five of their six games against promoted clubs, winning the past five in a row.
Alexander Isak has scored in each of his past four Premier League away games, with no Newcastle player ever doing so in five in a row.
Liverpool victory good news for fifth Champions League spot hopespublished at 10:56 22 January
10:56 22 January
Simon Stone Chief football news reporter
Image source, Getty Images
Liverpool's victory over Lille last night was fundamentally good for them in that they are through to the last 16 and have secured a top-two seeding.
However, that is also a positive for English clubs as a whole.
The countries who finish top in the European Performance Spots table will get five teams in next season's Champions League.
England are currently top - clear of Italy, Spain and Portugal - and while Aston Villa's defeat did not help, bonus points are applied for every position in the table, with teams in the Champions League getting the most.
So Liverpool are heading for a chunky 12 or 11.75.
There has been so much talk about how well Nottingham Forest and Bournemouth have done in the Premier League this season. Their chances of Champions League qualification will increase if English clubs keep doing well in Europe.
'No cause for concern'published at 12:25 21 January
12:25 21 January
Charlotte Robson Fan writer
Image source, Getty Images
They say all good things come to an end. And thus, Newcastle United's longest run of games won (nine) has done just that, with a comprehensive thrashing by Bournemouth. You can see why, in Eddie Howe's time away from management, he chose to go and learn from Andoni Iraola who at that time managed Rayo Vallecano.
Saturday just seemed like a match too far for Newcastle. Towards the end of our midweek game against Wolves we looked a little leggy and tired, but we were winning so convincingly it didn't really matter. Up against a more athletic, pressing opponent this weekend we could not cope.
I am not so knee jerk that I think it's the beginning of something terrible. It's possible that the players were just tired. I understand; January is tiring. We all feel a bit lethargic - it's a long month and it's ages to payday. Maybe that's the issue! It's probably that. I think what is notable for me is that the apparent tiredness of the players on the pitch didn't come hand in hand with any sort of poor attitude from Newcastle - it's true that Bournemouth got under our skin at points (*cough* Joelinton *cough*) but at no point did it feel, watching in the stadium, that the team had given up or didn't want to find a way to win.
I think that's the key thing that doesn't make me worry. Mix that with Bournemouth being the best side I've seen come to St James' Park this season, a week before our next game, and our next game being against Southampton (no offence Southampton) and I think there is no cause for concern.
More buoying still is the fact that Howe doesn't shy away from defeats - analysing them, talking about them, learning from them. Every team has an off day and I'm confident that's all this was. Better it happens on this weekend just gone than in the semi final we hope to put to bed in a couple of weeks.
Magpies 'fatigued' but 'important not to overreact' - Howepublished at 09:25 20 January
09:25 20 January
Image source, Getty Images
Newcastle boss Eddie Howe says it is "important" his side "don't overreact" following Saturday's disappointing 4-1 home defeat to Bournemouth.
The Magpies were hoping to set a new club record of 10 straight victories in all competitions, but struggled to continue the form that had seen them spoken about as outside title contenders against Howe's former side.
"I give credit to Bournemouth, I thought they played really well," Howe said post-match. "They were better than us.
"I think from our viewpoint we looked fatigued, we looked tired. The game in midweek took a lot out of us.
"From minute one we didn't look ourselves. Our usual zip, bounce, intensity wasn't there and we struggled to live with them. It was a frustrating watch for anyone connected with us. We have set such high standards but we fell well short of that."
Newcastle remain fifth - level on points with champions Manchester City in fourth - and Howe believes his team should not be disheartened after their fine run came to an end.
"It can happen at this level against any team," he added.
"Bournemouth have their way of playing and it's very difficult to play against and they can knock you out of your rhythm. We didn't have the answers to it.
"It is important that we don't overreact. It's one game. The players have been magnificent in recent weeks. We have to accept it, learn from it, analyse where we could improve and then come back next week."
Newcastle 1-4 Bournemouth - the fans' verdictpublished at 09:19 20 January
09:19 20 January
Image source, Getty Images
We asked for your thoughts after Saturday's Premier League game between Newcastle and Bournemouth.
Here are some of your comments:
Newcastle fans:
Chris: Newcastle have had a great run of results, and some fantastic performances, but the recent run has flattered defensive frailty. Too much being caught delaying distribution, misplaced passes and poor positioning (leading to reckless tackles and shirt pulls). Overall the team need to be more clinical and relentless.
Anth: Bournemouth were better on the day and deserved to win. They never let us settle and worryingly other teams will see this and no doubt try and replicate it. Eddie needs to regroup and start another run of wins. Bournemouth 'Newcastled' Newcastle.
Christopher: I say as a Magpie, thanks, Bournemouth, for exposing the ludicrous chat as regards our supposed 'title challenge.' We believed the hype and have received a deserved boot up the backside. If we'd just lost out, people might say we were unlucky. We weren't - we got a stuffing. Back to the drawing board for Eddie. And yet another yellow for Joelinton.
Theo: Two games in a row at home that the away team has started quicker than us. We built this run of wins on starting quickly. Maybe this was a bit of overconfidence?
A very off performance from the full-backs, it happens, they're young and improving. Perhaps more protection from midfielders would've helped. Final ball let us down and left Isak isolated.
However, can't complain too much and Bournemouth were excellent. Their movement off the ball to find space was exceptional. We had to drop points at some point, Southampton away (on paper) is a nice next game.
Bournemouth fans:
Bryan: Absolutely demolished Newcastle. It could have been six or seven. Get those passports ready?
Jonathan: To get a result like that at St James' says a lot about the team we have. Even with the amount of injuries we have, the team still believe in themselves and it is such a solid unit. We have a team a fraction of the price of others in the Premier League, but Iraola has them going toe-to-toe with the best.
We've had some horrid periods in our history, but it's an absolute joy to be a Cherries fan right now!
€11m for Kluivert, €10.25m for Semenyo, €26m for Adams. Bournemouth's shrewd transfer deals are paying dividends now.
Tom: Unbelievable, a truly magical performance. Sat in a hospital waiting room, jumping for joy listening and getting strange looks from other patients! Dare to dream, Cherries, dare to dream!
James: As a 50-year-old Bournemouth fan I can't think of a better performance I have ever seen. I can't quite believe what I'm seeing. Considering we have a thread-bare squad due to injuries, every player was superb. A thoroughly deserved win against a flying Newcastle. If I'm dreaming don't wake me up.
Gossip: Juventus interested in Kellypublished at 08:30 20 January
08:30 20 January
Juventus are interested in bringing Newcastle defender Lloyd Kelly, 26, to Italy - just seven months after he arrived from Bournemouth on a free transfer. (Gianluca di Marzio, external)
'We were off in almost every phase'published at 15:57 18 January
15:57 18 January
Image source, Getty Images
Newcastle manager Eddie Howe talking to BBC Match of the Day after today's game: "We were not at our best today, there is no doubt about it. Technically and physically we were not the team we've been in recent weeks and they played very, very well and made it a very difficult for us so full credit to them.
"I don't want to make excuses but I just felt there was fatigue in our performance today. We didn't start well and never played with the intensity we normally do and we were off in almost every phase. I'll put it down to physically right now but with a thorough analysis we'll see if I feel the same way.
"We made a big tactical switch at half time and throughout to try and invigorate us but it never happened. We have to respond and quickly. The big thing for us is we have a week in between so hopefully a change to recharge our batteries and then attack the game."
Newcastle 1-4 Bournemouth: Magpies crash back down to earthpublished at 15:46 18 January
15:46 18 January
Matthew Howarth BBC Sport journalist
Image source, Getty Images
Wednesday's victory over Wolves had lifted Newcastle into the top four of the Premier League for the first time in four months, but they were well below par against a Bournemouth side brimming with confidence themselves.
In-form striker Alexander Isak, who had scored in his previous nine club appearances, failed to register a shot from open play, with his only strike a disappointing second-half free-kick which flew straight into the Bournemouth wall.
Indeed, it took the Magpies 20 minutes to register any kind of attempt - a Joelinton effort from the edge of the box which sailed high over the crossbar.
Bruno Guimaraes cancelled out Justin Kluivert's opener, but Newcastle never stepped up after that and were punished for their profligacy in possession after half-time.
Kluivert's second and third goals were self-inflicted as Guimaraes and Anthony Gordon lost possession in the build-up, before Milos Kerkez rubbed further salt into the Magpies' wounds in second-half stoppage time.
It was a chastening defeat for Newcastle boss Eddie Howe, against the club where he was revered as a player and manager.
'Bournemouth were the better team and deserved to win'published at 14:59 18 January
14:59 18 January
Image source, Getty Images
Newcastle defender Dan Burn has been speaking to TNT Sports after today's defeat: "We didn't start very well. They set traps and we played into them quite a few times. It was hard to recover. Bournemouth were just the better team today, technically and physically, and deserved to win.
"They are very, very good on the counter. They've got some very good players and are very dangerous. They ask questions that a lot of other teams don't ask. They go quite long and direct and you don't come up against that as much in this league.
"We played in areas that we usually don't. We lost the ball quite a lot in the middle of the pitch. It is disappointing. We've been on a great run so we just need to dust ourselves down and go again.
"Those are the standards we set for ourselves. The work we've done throughout the season has been exactly the same."
Image source, Getty Images
