PINEHURST, N.C. >> Martin Kaymer has stretched his lead to six shots midway through the final round of the U.S. Open.

No one made was making much of a charge at the 29-year-old German, who was seeking his second major title. He captured the PGA Championship at Whistling Straits in 2010.

Kaymer birdied the third hole, took a bogey at the seventh, and rolled in an 8-footer for another birdie at the ninth. He made the turn at 1-under 34, pushing his overall score to 9 under at Pinehurst No. 2

Erik Compton, who has undergone two heart transplants, was Kaymer’s closest challenger. The Miami native shot 35 on the front side to remain at 3 under.

Only three other players were under par: Dustin Johnson, Henrik Stenson and Rickie Fowler, all at 1 under as they headed to the back side.

Fowler was playing in the final group at a major for the first time. But he had a miserable time at the fourth hole, where his second shot sailed off into the pine trees right of the fairway, then his next shot flew over the green. He needed to sink a long putt just to make double-bogey.

Kaymer opened the tournament with back-to-back 65s for a 10-under 130, the lowest 36-hole score in Open history. He struggled in tougher conditions Saturday but still managed a 2-over 72 that left him with a comfortable advantage at 8-under 202.

The conditions were more inviting than the previous day when only Fowler and Compton broke par. There was little wind, and some of the pins were easier to reach.

There already were eight scores in the 60s among those who had finished, led by Daniel Berger with a 4-under 66.

But it was another frustrating day for Phil Mickelson, who didn’t come close to completing his career Grand Slam. The six-time runner-up didn’t break par all week, finishing with a 72 that left him at 7-over 287.

The world’s top-ranked player, Adam Scott, turned in a 69 to wind up at 282.

Zach Johnson had the shot of the day, acing the 172-yard ninth hole.

Johnson’s 7-iron landed about 20 feet left of the flag, bounced twice, and curled down the slope into the cup. The player flung his club in the air while the gallery roared, then took off on a hand-slapping celebration along both sides of the ropes. After retrieving his ball from the hole, he tossed it into the crowd.

There were only six players under par heading to the final round. Fowler and Compton were the closest challengers to Kaymer, both five shots back.

Kaymer seemed to be playing a different course the first two days, making 11 birdies and only one bogey. The third round was more of a grind, with the leader making five bogeys. He offset his bogeys with an eagle at No. 5 and a closing birdie on the 18th, leaving him firmly in control.

The only player to squander a five-shot lead going to the final round was Mike Brady in 1919. He shot 80 and lost to Walter Hagen in a playoff the following day.