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What a Saturday of major championship golf - and the best part is it's set to be even better on Sunday!

We've got Phil Mickelson going for history and going head-to-head with Brooks Koepka, a trio of South Africans challenging and Bryson DeChambeau lurking just behind them.

The wind is set to increase, and so will the drama, especially along that tough closing stretch, so make sure you join us on Sunday for live coverage of every twist and turn as we find out who will be the 2021 US PGA Championship winner.

Meanwhile, see our round-up below, along with a full blow-by-blow account of how Saturday unfolded.

Also, click here for our full third round report.

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Well, they call it moving day and there was movement all over the place, but Phil Mickelson remains at the top but with just that one shot advantage over Brooks Koepka as the two Americans will battle it out in the final group on Sunday.

Mickelson had led by five shots at one stage as he threatened to run away with it, but some driving difficulties including a trip to the water saw him squander three shots in two holes before recovering his composure to finish strong.

Koepka was tied with him but bogeyed the last to slip one behind.

Mickelson will bid to become the oldest ever major champion on what should be an enthralling Sunday with the weather set to make conditions even more tricky.

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Former Open champion Louis Oosthuizen is just a shot behind Koepka and will play alongside American Kevin Streelman on Sunday, while two other South Africans Branden Grace and Christiaan Bezuidenhout will play together after both finished in a tie for fifth on three under.

Bryson DeChambeau is not out of it on two under after he birdied the last in a solid if unspectacular round of 71, while Paul Casey is at one under, six shots back, and even Jordan Spieth down at even par may be able to apply some pressure if he can card another 68.

What today did show us is that you can take nothing for granted over the Ocean Course's punishing finishing stretch.

-7 Mickelson

-6 Koepka

-5 Oosthuizen

-4 Streelman

-3 Bezuidenhout, Grace

-2 DeChambeau, Niemann, Woodland

Selected others

-1 Casey

E Spieth, Fowler, Finau, Fitzpatrick, Laird

+1 Lowry, Zalatoris, Poulter, Harrington, Laird, Matsuyama

+3 Rahm, Hatton, Hovland

+4 MacIntyre, Rose, Westwood

+5 McIlroy

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Phil Mickelson says he is playing better than his score showed today, and he's all about his mental approach on Sunday:

“I’m having a lot of fun, I’m enjoying it and playing well, I made some good swings played some good shots and I’m really having a lot of fun

“This has been a fun challenge and I'm looking forward to tomorrow’s round.

“I hit a lot of good shots all day today, but I let my mind lapse on a couple of swings and this course will penalise you for that.

“I got away with it a couple of times today but I did not get away with it on 13 and I just need to be a little bit sharper on every single shot and I think tomorrow I can shoot the score that will reflect how I’m playing.

“Not that I’m disappointed with two under, but it is not what it should have been.”

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Brooks Koepka speaking to Sky Sports: “That was the worst putting performance that I think I’ve ever had in my career. I struggled so bad. The putting green is so much quicker than when you get out there. I'll have to start banging them into the back of the cup.

"Anything inside 10 feet is usually running three or four feet by and then my putt on the last barely got to the hole, so I have to work on that.

"From growing up you just take it one shot at a time, don't get ahead of yourself, you don't get down, you don't get up and you just keep grinding and see what happens."

Phil Mickelson becomes the fourth player to hold the 54-hole lead/co-lead in a major at age 50 or older in the modern era (1934-present). The others are:

• Tom Watson, 59, 2009 Open Championship
• Greg Norman, 53, 2008 Open Championship
• Julius Boros, 53, 1973 US Open

Anthony Wall
Two-time European Tour winner on BBC Radio 5 live

Mickelson wants to prove a point. Today was probably the hardest day. It was about staying in it and keeping ahead. I don't think he will fear winning.

Louis Oosthuizen from 35 feet is again lacking in pace with his birdie putt up the 18th green. He's left himself another three footer. And he's going to have to wait until Phil Mickelson has made his par attempt.

He settles over the ball, nudges it forward... and it drops. The cheers from the fans are huge. Barely a flicker of emotion from Lefty, who merely touches his cap in appreciation.

A two-under 70 gives him a one-shot lead over Brooks Koepka.

Just Louis to finish up. Par. The South African will start Sunday's final round one shot further back.

Anthony Wall
Two-time European Tour winner on BBC Radio 5 live

To get the ball to stop within six feet was magical. It is a fantastic golf shot.

I thought anything inside 10 feet would be awesome. That was glorious.

Aside from the par-three 17th, Phil Mickelson has had a bit of scrambling back nine after an immaculate four-under-par front nine.

Since then, Lefty has pulled a couple of drives, tugged a couple of approaches and not been quite as precise with his wedges as usual.

What's he got left in the tank here? Plenty!

Mickelson flights it all the way and almost pitches it in the hole on the second bounce. A four-footer left for par.

Anthony Wall
Two-time European Tour winner on BBC Radio 5 live

Mickelson's had three or four loose shots on the back nine. As soon as he hit that he said 'what am I doing'.

It'll be tricky one now. He has so much fringe to go over. he might take the aerial route but at this time on a Saturday with so much pressure that is a real risky shot.

He is pin high but it is a nasty one.

Louis Oosthuizen doesn't need a drop and his ball is sitting quite nicely in an area that has been well trampled by the spectators.

He's taking no risks here though. The hole is tucked over on the left edge of the green, so Louis aims dead centre. He'll be hoping for a two-putt par from there.

Phil Mickelson has removed his shades. He means business. But that's not the shot he was trying to execute. The ball scuds out to the left of the green, missing by quite some distance. The shades go back on.

Poor finish from Koepka and it costs him what could be a huge shot. The put from off the back of the green wasn't the best and he couldn't rescue par in the end.

It's a round of 70 for the two-time PGA champion and as it stands he'll start just a shot behind Phil Mickelson and play alongside him in the final pairing tomorrow.

Lovely finishing birdie for Grace to get back to three under, he's had his struggles today but to finish still well in touch is huge - plus he'll play alongside fellow South African Christiaan Bezuidenhout tomorrow.

As the clock ticks over into Sunday morning, Phil Mickelson prepares to hit one last drive. It's a high cut, starting out right and bending back into the fairway. One hop too many but first cut is fine.

Louis Oosthuizen waves his driver out to the left after tugging his drive. Excitable punters dance around the ball as it bounces into a non-socially distanced throng.

All over. Get a good night's sleep Hideki Matsuyama and try not to think too much of that back nine.

Until then and six dropped shots, including one at the 18th, the Masters champion was looking very good value to be in the mix on Sunday.

Louis Oosthuizen is first to hit his birdie putt. It's not great. Leaves himself with a three-footer for par. Not what you need when you've just missed a short one on the previous hole.

Here's Phil. Starts his putt left. Stays left. But crucially, just 18 inches from the hole. Still marks it.

Louis. Nervy. Pulls it. Bogey.

Phil. Confident. Par.

Koepka has gone a little long and a little left of the 18th green so will need to keep his nerve again to get up and down and save his par.

He doesn't want to be finishing on anything less than seven under.

Anthony Wall
Two-time European Tour winner on BBC Radio 5 live

It was a soft draw. It is exactly what Phil Mickelson would have visualised. Mentally this was the one danger shot. This was the potential card-wrecking hole.

The wind is helping a little on the par-three 17th, blowing from right to left at about 7-8mph - and that means it's helping keep the ball away from the water. In theory.

Louis Oosthuizen is first to play. Heart in mouth time. His ball sneaks over the pond and is on the green. And breathe.

Phil Mickelson has a six-iron. 207 yards. The tracer suggests this going straight at the flag. Oh my. What. A. Shot. Given the pressure he is under that was sensational.

He's still got a 12-footer for birdie. But that was tremendous.

Nervy - that's the word to describe Koepka on the 17th green when he tickled his birdie try and left himself a horrible six-footer to save his par.

Koepka doesn;t really give anything away, but you could see the relief in his eyes - he's feeling the pressure alright - it's all about hanging tough these last two holes.

Imagine what they'll be like tomorrow!