Don't forget you can listen to live commentary of this closing round on BBC Radio 5 Live - or click on the link on this webpage.

Iain Carter and the team will talk you through the action right up until the final putt drops.

Just click the link.

Ian Poulter curls in a lovely right-to-left putt on the 10th for a birdie to move back under par.

He will be annoyed by a couple of bogeys earlier in his round that have probably pushed him too far back to challenge.

Bryson DeChambeau has an outside chance to move into the share of the lead on the par-four sixth. It's a 40-footer, curling in from the left. The pace is perfect, the line a fraction out.

A fifth par to go with his birdie on the fifth.

We are approaching one hour since the last group began their round and there are five former major winners within two shots of Russell Henley's lead.

Wouldn't want to think too much about that if I were him.

The American is back on the fairway out of the deep rough and it would take Bryson DeChambeau-level muscles to get it onto the green from there. Work to do for par.

Rory McIlroy is not happy with his second shot either. It's on the green, but way over on the left and he'll need a solid two-putt for par as well.

What an approach to the turn for Paul Casey.

He follows up birdies at seven and eight with another at nine - and it was almost even better, his attempted eagle putt pulling up just short.

He's bang in this now if he produces a back nine of similar quality.

Bryson DeChambeau muscles another huge drive, this time down the 500-yard par-four sixth. He chops off a huge chunk of the corner and his ball bounces in the fairway before dribbling back into the rough.

No bother from there though, a wedge scoops the ball up high and on to the green. No spin though, his ball scooting through to the back edge.

Finding the sixth fairway is tricky, but McIlroy hits one of his best tee shots of the day to do just that.

Should be on the green for two here. A birdie would be nice...

Leader Russell Henley cannot follow suit and he's in some nasty-looking rough to the right.

Matthew Wolff makes a 25-footer look like a tap-in on six.

Having dropped back to one under early in his round, the American is right back in the mix.

Jon Rahm misses his birdie just right but remains in touch too. Fluctuating is the word for this final day.

Ooft. That was so close.

Rory McIlroy crouches to the floor as his birdie putt - which would have seen him share the lead - is a rattlesnake's whisker from landing in the hole. Not to be. Pars for him and Russell Henley.

(NB Rattlesnakes almost certainly don't have whiskers. Presume you're not here for a zoology lesson)

-5 Henley (5)

-4 DeChambeau (5), McIlroy (5) Hughes (4), Oosthuizen (4)

-3 Koepka (10), Morikawa (6), Wolff (6), Rahm (6)

Selected:

-2 Casey (8)

Louis Oosthuizen cannot recover from those poor two opening shots on the fourth as a bogey drops him back into the pack.

Mackenzie Hughes has a great chance to rejoin Russell Henley on five under but the Canadian is looking for a break that never comes on his seven-foot putt and it's only a par.

McIlroy pulls his second shot out of the sand ever so slightly left on the fifth.

I like his chances of a two-putt for par there. But then he may just reproduce the magic of the fourth-hole birdie to make this 40ft putt.

-5 Henley (4), Oosthuizen (3)

-4 DeChambeau (5), McIlroy (4) Hughes (3)

-3 Koepka (10), Morikawa (6), Rahm (5)

Selected:

-2 Casey (8)

Whether he's got a bit nervy because of those making progress behind him, I don't know.

But co-leader Louis Oosthuizen pulls his tee shot on the fourth into a fairway bunker, then turns away in absolute disgust as his effort from the sand falls well, well short of the green.

A tall task to save par and a share of the lead for the South African.

Mackenzie Hughes shows him how it's done, the Canadian landing a lovely approach on to the green within six or seven feet.

Rory McIlroy hasn't exactly been flawless off the tee today.

Flying high from the birdie on four, he's straight in the sand on the par-four fifth. It's a good lie on the flat so all is not lost.

The fifth hole is playing 450 yards today. Bryson DeChambeau knocks 350 of them off with his drive. It's the first fairway he's hit today and the world number five takes full advantage, chopping a wedge the rest of the way and spinning it in to three feet.

Birdie time for Bryson.

Paul Casey putts from off the green for a birdie on the par three eighth - that's successive birdies for the Englishman.

Still 10 holes left in his round but he'll need at least three more of those surely.

For a brief moment Justin Thomas threatened to get involved in the mix today. A couple of birdies midway through his front nine catapulted him up to within three of the lead.

But the world number two's hopes have disappeared on the par-four 10th. A snap hook goes out of bounds and leads to a double-bogey six.

An important par putt from Jon Rahm on the fourth - the Spaniard was in danger of cancelling out his opening two birdies with back-to-back bogeys but he keeps his nerve to avoid that fate.