Both Fleetwood and Koepka are forced to test out their chipping skills on 13.

Image source, EPA

Koepka uncharacteristically leaves his far short.

Fleetwood has a near identical shot but makes the near opposite mistake, overcooking his effort to fire it a decent lick past the hole.

Two tough par putts to follow.

Image source, Getty Images

Something of a red letter day for Eddie Pepperell. The 26-year-old Englishman was playing alongside his hero Sergio Garcia and guess what? He outscored him.

Pepperell signs for a round of 71, Garcia a 72. Those scores mean he finished above the Masters champion too.

Matsuyama does well to make par at 17 after he missed the green in two.

A lovely little chip with his third allows him to convert with the par putt.

Looks like he'll need an eagle at the last to stand of winning this outright though.

A birdie for a play-off perhaps?

Lee Westwood reacts to his round of four over and final mark of seven over.

He writes on Instagram: "The wind blew a bit and #erinhills, external finally played like the #usga, external wanted it to. A few more "creative" pins today! Not the finish I wanted but still enjoyed another#usopen, external . Next stop Royal Ascot!"

Well just as Harman misfires, Koepka bananas his tee shot on the par three 13th out right and will be forced to test out his short game.

Edgy stuff out there.

"It doesn't matter what I do on this hole the ball is going in the same place."

Justin Thomas doesn't like this tee box it seems and his ball is wayward.

Brian Harman catches the curse of this 12th. Perhaps JT has given it to him. Harman looks disgusted with that hook into the fescue.

Image source, EPA

Rickie Fowler keeps himself alive on 13 after a poor tee shot. His pitch onto the green leaves 10ft which he gobbles up for par. On 11 Brian Harman is kicking himself after watching a putt for the lead stay up.

Fleetwood does better than his partner with his birdie effort but still can't quite land it and has to tap in for par.

Koepka for his par putt now - five feet...drills it. Important hold.

Image source, EPA

Ouch. The cruellest of margins between ecstasy and agony for Koepka on 12 - his birdie effort to take the outright lead lips out viciously and he has a tricky par putt now.

US unless stated.

-13 B Koepka, B Harman

-11 H Matsuyama (Jpn)

-10 T Fleetwood (Eng), R Fowler

-9 X Schauffele, B Snedeker, J Thomas

-8 B Haas, C Hoffman

-7 T Mullinax, S W Kim (Kor)

-6 P Reed, R Henley

Selected others: -5, Steve Stricker, JB Holmes, B Wiesberger (Aut), B Steele, -4, D Lingmerth (Swe), S Garcia (Spa), -3, E Pepperell (Eng), L Oosthuizen (SA), -2, P Casey (Eng), -1, Z Johnson, J Lovemark, M Lieshman (Aus), E, M Laird (Sco) +1, J Speith, M Kaymer (Ger), M Fitzpatrick (Eng), +2, A Johnston (Eng), S Lowry (Ire) +7, E Els (SA), L Westwood (Eng)

View the full leaderboard here.

World number four Matsuyama is the highest-ranked player left in the competition and it's showing today.

He drills his seventh birdie of the day in a startling round so far. A par at 17, a birdie at the last perhaps and he'd post a clubhouse lead of 12 under.

Scoreboard pressure that.

Justin Thomas pings an iron into the 11th green. He's trying to hold the wind with that one and his ball kind of listens but leaves a lengthy birdie putt.

On 13 Rickie Fowler is in trouble on the par three. His ball refuses to skip up onto the green and he will not be putting with shot two. Ugly effort that one.

Brian Harman looking to wrestle the lead on 11 with a superbly judged approach. His ball rolls through the fringe of the green and onto the surface to leave 12ft.

Sumptuous second shot from Fleetwood on 12 - he'll have 16ft or so for birdie.

Anything he can do, Koepka can do better today. Or just as well in this case as the American also sets up another birdie chance.

Image source, Getty Images

Rickie Fowler plays downhill on this 12th green. Perhaps 40ft to conquer. He goes hard and heavy, walking as his ball rolls past the cup. The man in orange pants needs this save but the miss leaves a pain in his belly.

Big response to dropping a shot at the last by Matsuyama on 16.

He twirls his tee shot on the par to around 10ft from the hole and has a chance to move back to 11 under.

BBC Sport app users may have to click the link above.

Always tough to rescue from the fescue and the rough claims Matsuyama as its latest victim.

That error off the tee ends up leaving him a 37ft putt for par and it's a noble effort but off track as Hideki settles for bogey and his charge is checked.

Image source, Getty Images

Rickie Fowler crushes his ball up the 12th after a delay on the tee and the ball nestles in the first cut, no disaster.

Brian Harman from the back of the 10th green, needs to get it in close. His touch has been on all day, lagging up for fun. He should make par from there now.

Back to Fowler, whisks it out of the first cut and the ball runs onto the green but rests a long way from the cup. Harman rolls home. Mr Steady.

Image source, Getty Images

Scottie Scheffler has won the race to be the leading amateur at the US Open. He closed with a one-over-par 73 but that was good enough to finish on one under and beat fellow American Cameron Champ.

Champ, who had been winning the battle all week, dropped three shots on his front nine and a crucial fourth went on the 17th to see him finish with a 76 for a level par total.