Martin Kaymer will take a five-shot lead into the final round of the US Open but he found day three of the 114th US Open far tougher than the first two.
The 29-year-old German had a record-equalling six-shot lead at halfway after back-to-back rounds of 65 at Pinehurst No 2, but his third round of 72 was far from plain-sailing.
Kaymer, who made only one bogey over the first two days, had five of them through 15 holes as the field struggled with dry, slick greens and tricky pin positions.
The leader needed three shots to get down from just off the green at the second, making his first bogey of the round.He missed a good birdie chance at the third before making another bogey at the fourth.
But that fourth hole could have been a lot worse and may even have steadied him down.
Kaymer drove into the pine trees left of the fairway, the ball settling in a washed-out patch of sand. He took a one-shot penalty, dropped the ball a couple of club lengths away, and punched out into the fairway.
From 160 yards, he struck a brilliant shot that settled 15 feet from the flag, then rolled in the putt. Even though it was a bogey, he gave a fist pump when the ball slipped into the cup.
Kaymer missed the fairway off the tee at five, but his second shot 202 yards from a waste area was as close to the flag as anyone got all day. He made the 5-footer for an eagle that pushed his score right back to 10 under.
Even though he dropped another shot at the sixth, a sloppy putt leading to his third bogey, some brave par saves got him to the turn at one-over 36.
He made another bogey at the 13th, then hung a birdie putt on the lip at 14.
His final error of the day came at 14 when he missed a four-foot par putt, but three pars and then a superb birdie three at the last moved him five shots clear of his pursuers.
Americans Rickie Fowler and Erik Compton both made light of the difficult conditions on day three to shoot three-under 67s for a share of second place.
At five adrift, the pair will feel they have a glimmer of a chance to win their first major title on Sunday.
Compton, a two-time heart transplant recipient, reeled off four birdies and an eagle in a seven-hole span to surge into contention.
"The conditions are extremely difficult," he said. "But when it gets really hard, that's when I seem to get really focused."
Fowler is one of the most popular players at Pinehurst, but he has only one career victory on the PGA Tour.
"I just hung in there," Fowler said. "I hit a lot of great shots into the greens, and got up and down when I needed to."
American Brendon Todd was the closest challenger to Kaymer heading into the third round, but he plummeted out of contention by playing the first nine holes at five over and eventually signed for a 79.
Swede Henrik Stenson and American Dustin Johnson both carded 70s and are six shots adrift of the lead on two under par.
England's defending champion Justin Rose is on one over par after a 70, while Rory McIlroy's 74 saw him slip to three over.