Koepka's got the Oak Hill cheat code today as his putt never leaves the hole before dropping for a third birdie in a row - that's some start to your final round when leading a major!

Hovland manages to knock in his birdie putt to keep the lead at three, but Koepka is motoring here and looks tough to stop.

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A Mixed bag could aptly be applied to Callum Tarren's round.

The Englishman, who is yet to win an event on the PGA Tour, finishes up with eight birdies on his card today but sadly there are also three bogeys on there plus a triple that came on the 16th when he struggled to hack out of the junk at the back of the left green.

Rory, Rory, Rory... you just knew it was coming. Pressure off, swing freely and the birdies follow.

He rolls in his 15-footer on the par-four sixth for a brilliant birdie.

He's back in the red but surely too far back now given what's happening elsewhere...

They've got this fourth hole surrounded with nice wedge shots in after both Hovland and Koepka laid up on the 614-yard par five. No more than six feet for either so you'd fancy these to drop.

Justin Rose rolls a birdie opportunity wide right on the par-three fifth hole.

It's not far away but right now pars aren't enough the way leader Brooks Koepka is going.

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Regulation pars for both Rory McIlroy and Michael Block on the par-three fifth.

They head to the sixth tee. Every player has said this is possibly the hardest hole they've faced in a major.

Water everywhere, bunkers everywhere, rough everywhere.

Rory is left but finds a trampled down area and hooks a beauty round a tree and into the heart of the green. He's got a 15-footer for birdie coming up... he's probably out of this but you know he's going to make a few birdies - can he keep the bogeys off the card though?

Cracking response from Corey Conners to that dropped shot on four.

He's flaunted his iron skills all week and there's another one for the scrapbook on the par-five fourth.

It's a birdie putt from three feet and he duly taps home.

Bryson DeChambeau's played tag team with the rough down this hole, which makes it tough to claim a birdie.

Another long putt drifts by and it's four pars in four holes.

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Almost a replica of the second hole where Justin Rose escaped from a bunker to chip in for par - except this time it would have been for birdie.

However, it just drifts by the right of the hole and he has to settle for par. He'll take that considering where he was in the sand. Real tough shot he had there but he made it look simple.

Tyrrell Hatton is doing Tyrell Hatton things. The Englishman, who was a bit of an outside bet this week adds to his birdie at the eighth with back-to-back birdies on the 11th and 12 holes.

Unfortunately he then goes and bogeys the 13th after sending his tee shot right and then failing to drop in a six footer for par.

The winner at the Arnold Palmer Invitational in Florida earlier this year Kurt Kitayama is making strides as well.

A fourth birdie of the day on eight puts him up to one under par, alongside Patrick Cantlay.

Another American leapfrogging Rory McIlroy.

As he rips another drive off the fourth tee that finds the fairway, Brooks Koepka certainly looks a lot like the Brooks Koepka that was almost unbeatable in the majors for a stretch when he gobbled up four in the blink of an eye.

If that guy is back then he could walk away with this one.

The 615-yard par-five fourth is not proving too kind for Justin Rose who deposits his third shot, from the middle of the fairway, into the bunker just before the green.

A battle to save par for the 2013 US Open champ.

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It's another scintillating iron shot from Koepka, off the tee this time at the par-three third sticking it to four feet from 212 yards - and the following birdie is inevitable.

Hovland can only par so the lead is three and looking ominous for the chasing pack.

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Down the leaderboard, Patrick Cantlay is getting a handle on Oak Hill and he's just picked up his fourth birdie of the day at the 10th hole.

He's up to one under par and could make further inroads as he takes on the amenable first half of the back nine.

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We haven't seen much of Rory McIlroy for a while. He's been on the long par-five fourth, and he's made a bit of a hash of it.

In the rough off the tee, chopping forward with his second and leaving 140 yards into the green with his third.

A bit of a misjudgement though and his ball is 40 feet from the pin. And then he compounds that with a poor putt through the break and misses the five-footer coming back. Scruffy bogey and that opening birdie suddenly feels a long, long time ago...

Sepp Straka cards his fifth birdie of the day over on the 10th hole. A wedge into six feet teed that up nicely and but for bogey's on the fifth and ninth, the Austrian would be looking at a place in the top seven.

As Brooks Koepka picks up a birdie, Corey Conners is falling further back.

He can't get up and down in two and it's an early setback for the Canadian.

Bryson DeChambeau is solid though, chipping out and rolling in to stay at three under.

Koepka strokes his birdie putt in with ease on the second to move to seven under and a two-shot lead - with Hovland getting his effort all wrong as it breaks away to the right.

Koepka looks supremely confident here and the challengers aren't exactly all over him....yet.

Both Corey Conners and Bryson DeChambeau have been good on par threes this week.

Not for their first one today though.

Their balls both go left off the tee and are re-acquainted in the dense rough over there in front of the punters.

That'll test their scrambling skills.

Stunner of an approach to the second by Koepka to about four feet it looks like...but Hovland only goes and matches it!

If these two can spur each other on like this we're in for a treat.