Were you at the game or following from elsewhere?
Have your say on Leicester's performance, external
What did you make of West Ham's display?, external
Come back to this page on Wednesday to find a selection of your replies
Two matches make up Tuesday's Premier League action, and we will bring you every moment.
Ipswich v Crystal Palace (19:30) - listen on BBC Radio 5 Live
Leicester v West Ham (20:15) - listen on BBC Radio Sports Extra
All kick-off times GMT
Follow all of the action and reaction here
James Jones
Fan writer
Image source, Getty ImagesA few days is a long time in football.
On Monday night there was a glimmer of hope that things might be improving after West Ham went to St. James' Park and deservedly came back with all three points.
But by Saturday night it felt like we were back to square one and questioning Julen Lopetegui's ability to turn things around.
I wrote last week that all we wanted to see after the Newcastle win was a similar performance against Arsenal. There was no expectation we would win, but there was an expectation that the performance would continue to show progress.
Conceding five goals at home suggested there are still so many issues that need to be fixed. The quality of the opposition is irrelevant. For much of the past four years, we were very difficult to beat, even against so-called 'top six' sides.
But this season we have shipped five goals twice and look so fragile defensively that it is a mystery we have not conceded more.
The win against Newcastle will have saved Lopetegui's job in the short term. He will have the next few games to prove to everyone that the Arsenal defeat, and the manner of it, was just another blip in his long term vision.
To earn any trust that he has a future in east London, he simply has to ensure we go to Leicester on Tuesday night and win.
Saturday was more about the performance and not the result. Tuesday is all about both.
No excuses.
Find more from James Jones at We Are West Ham, external
Chris Sutton is making predictions for all 380 Premier League games this season, against a variety of guests.
For week 14 he takes on James Ryan, bassist with rock band The Slow Readers Club.
Sutton's prediction: 1-2
Both teams were beaten heavily at the weekend and this feels like a massive game for West Ham boss Julen Lopetegui, who is back under scrutiny again after such a big defeat at home by Arsenal.
What might help him here is how bad Leicester are defensively. This is Ruud van Nistelrooy's first game in charge of the Foxes so you would expect King Power Stadium to be rocking, but that will not help them keep the Hammers out.
I am not convinced by West Ham in any way, shape or form at the moment but they have attacking players who can hurt Leicester, and that will get them the win Lopetegui needs.
Ryan's prediction: 1-0
This has got 'new manager bounce' written all over it.
West Ham are considering Porto boss Sergio Conceicao as a replacement for Julen Lopetegui, whose future as manager is under increasing pressure. (Guardian), external
Meanwhile, the Hammers have decided to offer Vladimir Coufal a new contract rather than offload the 32-year-old right-back. (Football Insider), external
Want more transfer stories? Read Tuesday's full gossip column
Image source, Getty ImagesWest Ham have been drawn to play Aston Villa in the FA Cup third round at Villa Park.
The tie will take place between 9-13 January.
West Ham boss Julen Lopetegui has been speaking to the media before Tuesday's Premier League game against Leicester City (kick-off 20:15).
Here are the key lines from his news conference:
Centre-back Jean-Clair Todibo is the only injury doubt following the defeat by Arsenal as he is awaiting further assessment.
Striker Niclas Fullkrug "is improving and is very close" to a return, but it is unlikely he will be available for Tuesday: "Three months is a long time without matches, but thankfully he is close to recovery."
Mohammed Kudus has completed his five-game suspension and is "fit and ready" to return to the matchday squad.
On the heavy defeat to Arsenal: "We are focused on the next challenge. I prefer to talk about tomorrow than the last match, because that's the past now. We were disappointed."
He said Leicester "will be very tough and demanding" opponents and added "I am sure we need to show our best version to compete there."
On facing a new opponent in Ruud van Nistelrooy: "He is a very good manager - he has shown that before and has done well in the Premier League. One of the difficulties when you face a new manager is that you don't really know what he's going to do."
Follow all of Monday's Premier League news conferences and the rest of the day's football news
Image source, Getty ImagesWe asked for your thoughts after Saturday's Premier League game between West Ham and Arsenal.
Here are some of your comments:
West Ham fans
Kevin: The whole team started the game slowly and soon found themselves three goals down. With a poor defence and practically no midfielders, Arsenal had time and space to play the ball around as they wanted. West Ham only livened up when they found themselves four goals down. A better second-half performance, but it was way too late then.
Andy: They looked like schoolboys. Lazy and silly mistakes giving away those penalties. The Hammers need to wake up. They haven't moulded the best team for this season as yet and it shows, unfortunately. The manager seems to change the team all the time, but time is moving on. It will be about survival this season. The fans have faith but we don't have the talent.
Anthony: A defensive shambles. The fans wanted open, attractive football but the administrators and players interpreted this as a licence for a non-tackling, minimum effort and lack of discipline approach. They are lucky the bottom four teams are so poor, otherwise they would be relegated.
Fred: West Ham had no idea how to defend against Arsenal. The two centre-backs were poor and the midfield were static, making no opportunities for the three forwards. Michail Antonio was supposed to be marking Gabriel on corners, but he totally lost him. Max Kilman was poor. Arsenal were a class above and Bukayo Saka was world class. I'm disappointed with how West Ham played.
Arsenal fans
Vince: The second set of five goals within five days makes for one heck of an intent. Martin Odegaard and Saka were imperious and hopefully they will stay fit for the rest of the season. Perhaps they shouldn't play at all in domestic cup games. We have waited far too long for a league title!
Sam: Total dominance by Arsenal in the first half, despite two very good goals by West Ham. You would expect the Arsenal substitutes to come on, prove they should be starting and put some gloss on the scoreline but unfortunately they just aren't at the same level as the first team.
Olivia: I am a firm supporter of Arsenal and I have watched (and cried) over the last three seasons. This season I have been upset but now I am so happy that Arsenal are making the comeback they deserve! Odegaard is the glue we needed. Saka and him play beautifully! I'm so happy, I'm just waiting for our well-deserved trophy lift!
Luigi: We are within the grasp of something great, but we need to stay humble and keep working towards our goal. This team has something special and you don't have to be a fan to see it. West Ham couldn't cope but I give it to them, they hung on in there. Mikel Arteta deserves to win something major - he has brought us out of deep water and got us believing again.
Image source, Getty ImagesFormer Liverpool midfielder Danny Murphy has criticised Julen Lopetegui's side for "not doing the fundamentals well enough" against Arsenal, leading to a 5-2 thumping on home soil.
"I was really shocked how easy West Ham made it for Arsenal," Murphy said on Match of the Day. "They were basically not doing the fundamentals well enough. They struggled with the real basics of football.
"[Michail] Antonio, as your centre-forward, was marking their best header of the ball - I found that strange. He left him, he lost him, he didn't seem comfortable doing it. Gabriel is the best header in the Premier League from set-plays.
"[Max] Kilman, who is arguably West Ham's best header of the ball at centre-back, should have been marking Gabriel.
"They lacked communication and they were not winning their second balls - the normal basic things. They were letting [Martin] Odegaard - one of Arsenal's best players - just run. The most creative player on the pitch was in oceans [of space].
"Bukayo Saka - one of the best finishers on his left foot in the Premier League - was left in the 18-yard box with no-one even within 10 yards of him. Unbelievable. Surely they worked on that? You can't do that.
"These are the fundamentals - winning duels, closing down space, tracking runs, being competitive against a good side.
Image source, Getty ImagesIt is one of the most eagerly anticipated dates in the football calendar as Premier League and Championship clubs join the FA Cup action from round three.
The draw will take place on Monday, 2 December from 19:00 GMT and can be watched live on BBC Two and BBC iPlayer.
Gary Lineker introduces highlights and analysis from Saturday's five Premier League fixtures, plus the best of the action from Friday's game between Brighton and Southampton.
If you missed Match of the Day, you can catch up now on BBC iPlayer.
Listen back to full match commentaries on BBC Sounds:
Image source, Getty ImagesWest Ham United forward Jarrod Bowen has been speaking to Sky Sports about Arsenal's dominance: "There was a lot down to us - how we were without the ball and making a couple of mistakes as a team. We worked hard at set-pieces, knowing they were a threat. It was two penalties and they are just frustrating goals to concede.
"We were fighting back and we got to 4-2. I felt that if we got in at half-time at 4-2, then there was an opportunity."
On the second-half performance: "Then in the second-half we had a go. The fans were brilliant, but ultimately we weren't good enough.
"The positive is that we play [again] in 72 hours and games are coming up thick and fast. Tomorrow is a new day and it is all focus towards Leicester."
Image source, Getty ImagesWest Ham United boss Julen Lopetegui has been speaking to BBC Match of the Day following the defeat: "Overall, I am frustrated with the first-half. We deserved two goals, but they didn't deserve five.
"We were unlucky in the decisions, in my opinion. The first goal, I think it was a block."
On Lukasz Fabianksi fouling Gabriel in the box: "I think it was a bit soft. We were unlucky. We have to do better for sure. We didn't make good decisions in a defensive way - that's why it was a strange match.
"The team showed character to compete. We were unlucky with the decisions today. We asked before the match, the referee with the block, as a coach we have to know the limit.
"This week we have to do better in our individual actions, in a defensive way."
On having to watch on from the stands: "It is always difficult to not stay on the bench because you can't help the team, and I was very frustrated."
Image source, Getty ImagesAaron Wan-Bissaka has scored two goals in his last two Premier League appearances, as many times as he had scored in his first 182 games in the competition.
Emma Smith
BBC Sport journalist at London Stadium
Image source, Getty ImagesBefore the game, optimism abounded at West Ham after their impressive win at Newcastle on Monday. The on-field announcers, sporting Christmas jumpers, were confident of a win.
That optimism was shot to pieces by an opening 35 minutes in which Arsenal were at times irresistable, but where West Ham were often their own worst enemies.
The marking for Gabriel's opener was sloppy, Lucas Paqueta's lazy trip on Bukayo Saka conceded a penalty, and it was 0-4 when Max Kilman failed to intercept a route one ball.
It meant West Ham never really looked likely to register back to back Premier League wins for the first time since March.
Manager Julen Lopetegui bought himself time with the Newcastle win, and the fans largely held off on booing in favour of backing the team.
But the Hammers cannot afford too many more hammerings like this.
Were you at the game or following from elsewhere?
What did you make of Arsenal's display?, external
Have your say on West Ham's performance, external
Come back to this page on Monday to find a selection of your replies
Five matches make up Saturday's Premier League action, and we will bring you every moment.
Brentford v Leicester
Nottingham Forest v Ipswich
Wolves v Bournemouth
Kick-offs 15:00 GMT unless stated
Chris Sutton is making predictions for all 380 Premier League games this season, against a variety of guests.
For week 13, he takes on boxer Sunny Edwards who is a Chelsea fan.
Sutton's prediction: 0-1
Julen Lopetegui really needed Monday's win at Newcastle after a difficult start as West Ham boss.
He and his side will be buoyed by that but this is not a good time to be playing Arsenal, who are purring again now Martin Odegaard is back from injury.
The Gunners were not in great form without Odegaard, but he makes them a different proposition and I am going to say he will make the difference in a very tight game.
Edwards' prediction: 0-3
Arsenal have got going again.
West Ham have approached Napoli over a January deal for 29-year-old Argentina forward Giovanni Simeone. (FootballTransfers), external
The Hammers are also considering a move for 20-year-old Brighton and Republic of Ireland striker Evan Ferguson. (FootballTransfers), external
Image source, Getty ImagesWe asked you to tell us one thing - good or bad - that nobody is talking about at West Ham.
Here are some of your comments:
Jake: Young players. There has been a significant lack of academy players breaking into the first team in the last three to five years. Debuts have been handed to some under-21 players in cup games, but apart from that, no one has broken into the first team and stayed there. There’s been hardly any players on the bench this season that the club has developed.
Nidge: As good as Aaron Wan-Bissaka has been this season for West Ham, is he competing for the same space on the pitch as Jarrod Bowen? Bowen has been so successful in cutting onto his left from the right side after Vladimir Coufal had overlapped in previous seasons, are we taking away one of our greatest strengths when Wan-Bissaka underlaps?
Joe: Watching West Ham on Monday night was a complete joy - a committed performance just as we needed it. The one thing I couldn't help but notice is that we had the oldest player in the Premier League starting in goal. Lukasz Fabianski has been a great servant, but let's look into a younger upgrade - someone who has good distribution to start those attacks.
Mike: No one is talking about the fact that we have the most talented squad we've possibly ever had. Once the key is found (and it may have been at Newcastle) then this group has the potential to be very, very good. The manager has taken the flak but we have a lot of new players and it has just taken a while for them to adapt.
Michael: The team and manager are under a lot of pressure after a poor start to the season, but West Ham are just four points off Spurs in sixth. It is a season of transition in terms of manager, players and style, and it may take time to find consistency, but maybe things are not as bad as they seem.
