Image source, Getty Images

Erik Compton, who is three under for the day and the tournament, might not be a hugely familiar name but he certainly deserves more recognition.

The 34-year-old American has twice undergone heart transplants, the first at the age of 12 and the second just six years ago.

His round is the best on the course today.

-10 Martin Kaymer; -3 Erik Compton, Brandt Snedeker, Kevin Na; -2 Henrik Stenson, Brendon De Jonge; -1 Rickie Fowler, Matt Kuchar, Dustin Johnson, Brooks Koepka, Brendon Todd

Selected others: +1 Adam Scott, Jordan Spieth; +2 Ian Pouter, Jason Day; +3 Rory McIlroy

Full leaderboard from US Open website , external

Kaymer stands over his eagle putt, it looks straightforward but these greens certainly aren't. It moves right to left but drops, a big moment for the leader who extends his advantage to seven shots. The hardest hole on the course up next. Can he survive the sixth?

John McEnerney, external: Nervy all round, that's the way its going to be for all of them today, you can't go for it or play it safe. Pinehurt not Pinehurst.

Martin Kaymer is on some sort of golfing rollercoaster.

He thumps an iron from the scrub on five to within 10 feet of the pin. It's a sensational effort which makes eagle and a return to 10-under possible.

This would be the perfect way to wipe out his two bogeys so far. Something tells me he will be hoping for fewer fireworks and more consistency.

The entire field is out on course and we have only two players under par.

Rickie Fowler and Erik Compton are both two under. Mix breeze with glass-like greens and what do you get? Chaos.

Jay Townsend
BBC Radio 5 live summariser at Pinehurst

"I think the key to Martin's round is the fifth hole. He's got to make sure he makes a birdie and then he'll get into the round and everything will be ok from there."

Remember that trouble we said Martin Kaymer was in? Well he handles it superbly and coolly rolls home from 15 feet for just a single dropped stroke.

There will be some doubt in his mind now surely after a troublesome run of holes. A par five to come, though, and the leader by five strokes has made two birdies on the fifth hole in the last two days.

Hear the roars as fans' favourite Rickie Fowler drops one in from 20 feet on the 10th hole to move to two under.

The Californian has been superb today and could yet still challenge for the biggest win of his career.

Image source, Getty Images

As the third day continues, the statistics suggest that the sixth is the hole which has posed the most problems so far.

It has yielded just 10 birdies as it stands, but has cost 126 bogeys, 11 doubles and one ominously named "other" score.

The 219-yard par three might appear relatively innocuous but players must flight a medium-to-long iron over a nasty crease that sits four feet below the level of the green, while avoiding one of the deepest bunkers on the course (pictured).

Even if they do manage to keep the ball on the dancefloor, a treacherous putt awaits anyone who goes past the pin.

Good luck, fellas . . .

Brendon de Jonge could hand Kaymer a reprieve as the man from Zimbabwe feels the full wrath of the par-three sixth.

He is not the first. The hardest hole on the course this week hauls De Jonge back to three under.

Jay Townsend
BBC Radio 5 live summariser at Pinehurst

"It's up against a wall of pine needles and if you move the pine needles the ball is going to roll down the slope. Kaymer is going to do well to get it on the fairway. He's looking at at least a bogey."

Martin Kaymer is in conversation with a rules official as his ball is in as horrible a place as you can imagine on the fourth hole.

Think of the worst position your ball as ever been in on your local course and treble it. There is dirt, pine straw, trees, pretty much everything short of wild animals.

He is querying if his ball can be moved because of the condition of the ground on which it rests, but the official is having none of it. It will be a penalty drop and surely a lost shot.

After two days of relatively benign conditions, Pinehurst No.2 has bared its teeth today and is playing more like a US Open track.

"We are delighted with it," says USGA executive director Mike Davis of the tournament. "It's a different type of US Open from 1999 and 2005 here, but in a good way. It's still a great comprehensive test of golf and the players have to hit all the shots.

"They have more options off the tee but they still have to get on the Donald Ross-designed turtleback greens."

Only three of the last eight US Opens have been won with a score of under par.

-9 Martin Kaymer; -4 Brendon De Jonge; -3 Brandt Snedeker; -2 Brendon Todd, Henrik Stenson, Kevin Na, Erik Compton; -1 Rickie Fowler, Matt Kuchar, Dustin Johnson, Brooks Koepka; Level Adam Scott, Jordan Spieth

Selected others: +1 Ian Poulter; +2 Justin Rose, Jason Day; +3 Rory McIlroy; +5 Phil Mickelson

Full leaderboard from US Open website , external

As Kaymer - who putted like a man possessed on Friday - misses a birdie opportunity from 10 feet on three, Brendon de Jonge rattles in a birdie on five and is now just five shots adrift.

The lead is slipping. Will this course have the final say and throw up a big turnaround.

The par three ninth has claimed nine of today's 236 bogeys and one of them belongs to Rickie Fowler.

After an impressive start, he gives a stroke back at the turn. The 25-year-old has never finished better than 10th at a US Open. He is currently tied seventh on one under.

Image source, Getty Images

Phil Mickelson, who finishes on five over par, still waits to land this priceless major. The man who beat him by a stroke in 1999, Payne Stewart, is immortalised in bronze behind the 18th green at Pinehurst as at 42, just months after his victory, he was killed in an airplane accident.

The three-time major winner was known for his overwhelming desire to win.

The statue by the clubhouse is our memorial," says Tom Pashley, the soon-to-be president at Pinehurst. "Everyone has their photo taken by it and does the pose. You've got to, you're at Pinehurst."

Brandt Snedeker dribbles a putt for birdie on the par-four third. It's for outright second place and to be just five off the lead but Pinehurst shakes its head. A lip out. Good luck getting that out of your mind on the walk to the fourth.

Martin Kaymer splutters on two. Hope for the chasing pack.

The German has a huge putt from off the green and leaves it 25 feet short of the cup. He cannot pull out another miracle as his fourth is off line. Only his second dropped shot of the week.

So go on then Brendon Todd, put the pressure on. No such chance, as he putts from on the green to off it and hole two claims two bogeys.