Brooks Koepka is demonstrating excellent control of his yardages out there as he finds the green on four with yet another terrific second shot. He could go to 14 under with another good putt.

What's that roar behind him though?

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Droppage. Kim Si-woo looks out of sorts early doors and an iron into a bunker on four ultimately takes one off his card. Rickie Fowler alongside him has to hustle to make his four too and a putt from 9ft just about takes the right side of the cup. Deep breath Rickie, job done... just.

The wind seems to aiding Charley Hoffman today - and not just because he's not sweating as profusely as yesterday.

After four pars, he makes a lengthy birdie putt at five and sets up another birdie chance on the par three sixth.

By the way, sorry Luke but I just can't agree that Entourage is a cracking pick for favourite TV show from Justin Thomas. I'm more of a The Wire fan.

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He may be dropping shots but you simply have to tip your hat to Justin Thomas' picks for his favourite film and favourite TV show.

On the big screen he opts for Shawshank Redemption.

"Get busy living or get busy dying," as Andy Dufresne said.

Thomas must feel alive today alright.

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On the little screen he is a fan of HBO hit Entourage.

Cracking pick. JT's putting is loose so far but he has his entertainment choices in good order.

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Fleetwood has a monster birdie chance...has he? Oof, just slides it wide and fortunately sees it hold up.

Koepka has half the distance to cover but it's another slow putt - that's too slow though and he leaves it short. Easy par.

Here comes Tommy for par - ack, he's pushed it. That's a big miss - he falls to two shots behind his partner.

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Brian Harman is below the level of the green on the second hole. He flew it with his second so needs an up and down to make par. That's a delightful chip and perhaps that will settle down a jittery start. He could blow that in.

Justin Thomas has caught some trouble on the same hole after being in the fairway off the tee. This is a real lapse. Putting from off the surface with his third he leaves the effort short and it doesn't even make the green. This now is for par and it's not nice at all, laced with evil... he misses. Bogey on an easy hole.

Sometimes it's not about when you go off, it's about who you're playing with.

As Thomas and Harman are scrambling in the final pairing, Koepka and Fleetwood seem to be driving each other on to greater heights at the moment.

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Fleetwood puts his second on three just off the green and should get down in two. Koepka follows with another stirring shot and will have a birdie look.

You have to birdie one - the fourth easiest hole out there. You have to birdie two - the second easiest hole out there. Then par the third - the toughest of the drags at Erin Hills statistically.

Brian Harman hooking it like the captain right now. This second hole is one where a birdie is important but his ball has just fizzed into some rough. That was wild.

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Justin Thomas gets it away clean. Some 277 yards will give him around 50 to the green.

The ability to keep the nerves in check and think clearly under pressure will no doubt play a part today. Knowing you can win and close out a tournament carries a currency then.

Looking at the performances of the main men in PGA Tour and European Tour events we can see they all know how to get over the line, though some do it more than others.

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Brian Harman would have gone to bed last night thinking 'do not make bogey on the par-five first.' He watches Justin Thomas make par and then has to line up maybe eight feet for his own par. This is a knee-knocker. He has gone big in wearing white slacks today... his ball is on the way and it's in.

Up on the third green Rickie Fowler has scrambled like a Sunday morning egg to save par. He got up and down from the edge of the green. Kim Si-woo gets it done too for his third par.

US unless stated.

-13 B Koepka

-12 B Harman,T Fleetwood (Eng)

-11 J Thomas, R Fowler

-9 S W Kim (Kor)

-8 H Matsuyama (Jpn), P Reed, R Henley, C Hoffman, X Schauffele

-7 B Haas, B Steele, JB Holmes

-6 B Snedeker, E Pepperell (Eng), S Garcia (Spa), D Lingmerth (Swe)

Selected others: -5, Bernd Wiesberger (Aut), -4, J Lovemark, L Oosthuizen (SA), -3, P Casey (Eng), E, Martin Laird (Sco), Marc Lieshman (Aus), +1, J Speith, A Johnston (Eng), +2, M Kaymer (Ger), +7, Ernie Els (SA)

View the full leaderboard here.

Superb judgement from Fleetwood on two, rolling a delicate birdie putt just up to and into the cup.

He makes it a three-way tie for the lead for all of 30 seconds, before Koepka steps up and drains his birdie chance to move to 13 under and seize the outright lead.

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Rickie Fowler has started well but compatriot Brooks Koepka looks to be going off even better.

The burly American has just flighted his second shot on the second hole very, very close. He should go birdie, birdie here.

Every day he's Schauffele.

Xander Schauffele is the latest to reach eight under, with a deftly-judged birdie putt on five.

The 23-year-old is making a name for himself this week - if his name alone wasn't already doing just that.

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Brian Harman was way right off the tee box as we know and took his punishment to chip back into the fairway. He is not a big hitter so will struggle to make the green with his third... indeed he's short. This is a par five so he will need to use his furniture to get home for par.

Justin Thomas, a young man who lists San Diego as his favourite city. He too was in the rough off the tee peg and wedged out. He's up on the green after an 8 iron for his third though. Birdie a long shot given the postcode between him and the cup.

Mastuyama's charge checked. Too keen on his birdie putt, firing it a tricky distance past the hole and failing to save par on the return.

So what happens if we have two or more golfers tied at the top of the standings after the final round?

We do it all again tomorrow, because the US Open remains the only major to have a full 18-hole play-off.

The last time it happened in 2008 was a belter.

Tiger Woods, hobbling round on a left knee missing an anterior cruciate ligament and two stress fractures of his left tibia, birdied the final hole of the tournament to force a play-off against Rocco Mediate.

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Not content with one golfing miracle, Woods did it again in the play-off - nailing a clutch birdie putt to force sudden death.

Then at the 19th play-off hole, Mediate bogeyed, Woods made par and a 14th major title was his.

A glorious finale but with a poignant tinge - Mediate has not come anywhere as close since and the 2008 title remains Woods' final major win.

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Right so all the contenders are out on course now and by the time Brian Harman swung his second shot, he was already no longer the outright leader as he was joined by Brooks Koepka.

It's all a bit congested at the top, to say the least. So what happens in case of a tie at the end? The answer follows next...