He appears to be playing an entirely different course.
Kaymer set the 36-hole scoring record at the U.S. Open on Friday with another 5-under 65 - this one without a single bogey - to build a six-shot lead over Brendon Todd and leave the rest of the field wondering if anyone had a chance to catch the 29-year-old German at Pinehurst No. 2.
''If you take Martin out of it,'' said defending champion Justin Rose, ''it's a great golf tournament.''
Kaymer was at 10-under 130, breaking by one shot the record set by Rory McIlroy at rain-softened Congressional in 2011.
''I heard he played the No. 3 course. Is that true?'' Kevin Na said after a 69 put him seven shots behind. ''It's unbelievable what he's done. Is 4 or 5 under out there? Yes. Ten under out there? No, I don't think so. I guess it was out there for him. I watched some of the shots he hit and some of the putts he's made and he looks flawless.''
The six-shot lead after 36 holes tied the U.S. Open record first set by Tiger Woods at Pebble Beach in 2000 and matched by McIlroy at Congressional. Woods wound up winning by 15 shots. McIlroy won by eight.
''I played Congressional and I thought, `How can you shoot that low?' And that's probably what a lot of other people think about me right now,'' Kaymer said.
Todd, who won the Byron Nelson Championship last month for his first PGA Tour win, made some tough par saves to keep bogeys off his card for a 67. He will play in the final group Saturday in his first U.S. Open.
Brandt Snedeker had a 68 and joined Na at 3-under 137.
Phil Mickelson was 13 shots behind after going back to his conventional putting grip and giving up too many shots. He had a 73.
Essentially, this tournament comes down to Kaymer.
''If he does it for two more days, then we're all playing for second spot,'' Adam Scott said.
Beyond Kaymer's dominance, here's five things to look for in the third round:
PINEHURST BITE: With heavy rains softening the greens, Pinehurst No. 2 has played a bit easier than expected. Still, there are only 13 players under par at the midway point in the tournament, and those pin positions aren't going to get any easier on the weekend. If the rain holds off, the turtleback greens will firm up even more, making it tough to go at the flag with abandon. At that point, it becomes more about damage control than putting up low numbers, perhaps improving the odds of closing the gap on the leader.
MAJOR INEXPERIENCE: Kaymer's closest pursuers don't have a lot of major championships on their resume. Of the next 18 players in the standings, only three have captured one of golf's biggest titles. Keegan Bradley (2011 PGA Championship) was eight shots back at 138, Rory McIlroy (2011 U.S. Open, 2012 PGA Championship) was another stroke behind, and Adam Scott (2013 Masters) faced a daunting 10-stroke deficit. For now, the leader doesn't have to worry about a bunch of major winners in his rear-view mirror.
LEFTY'S PUTTER: Mickelson abandoned the claw grip in hopes of improving his putting stroke. It didn't work. He had four three-putts on Friday and has taken 65 swings with the short stick over the first two days, leaving him tied for 135th in the tournament rankings. No wonder he said the ''hole looks like a thimble to me right now.'' A daunting 13 shots off the lead, Mickelson will spend the weekend more concerned with steadying his stroke on the green than making any sort of serious run for his first U.S. Open title.
BACK TO BACK: Like anyone not named Kaymer, Rose's hopes of winning the title look rather bleak at the moment. But at least he's still in the game. The defending champ shot 69 on Friday for a 1-over 141, leaving him 11 strokes off the lead. He'll need to make a big move Saturday to have any hope of chasing down Kaymer. There hasn't been a repeat winner at the U.S. Open since Curtis Strange in 1988-89.
KID IS ALL RIGHT: Nineteen-year-old Matthew Fitzpatrick is playing on the weekend in another major championship. The 2013 U.S. Amateur winner shot 71-73 to become the lone amateur to make the cut. Last year, he played in the British Open at Muirfield, finishing tied for 44th to earn the silver medal as low amateur. The other 10 not-for-pay players failed to advance at Pinehurst No. 2: Cory Whitsett, Hunter Stewart and Brian Campbell (all at 146) missed the cut by a single stroke. The others were farther back.
Follow Paul Newberry on Twitter at www.twitter.com/pnewberry1963