"It's fun watching him hit every fairway and every green and make every putt," said Keegan Bradley, one of Kaymer's playing partners for the first two days. "It was pretty awesome. . . . He's as dialed in as I've ever seen.
"He's just very steady. He doesn't seem to get up and down," Bradley said. "That's a pretty good combination for the U.S. Open."
The low-key Kaymer, winner of last month's Players Championship, was the beneficiary of a course softened by overnight rain. That enabled him to keep his confident, go-for-it mind-set on a layout fraught with peril.
"I was expecting the golf course to play a lot firmer," he said. "Obviously that rain helped a lot, and you could still be aggressive. We had perfect greens this morning, but still you had to hit good shots. Obviously the record shows that it's very rare that somebody shoots 10-under par after two rounds. I didn't expect it."
Kaymer's 130 broke the U.S. Open record of 131 set in 2011 by Rory McIlroy at Congressional. It also matched the lowest 36-hole score in a major, a mark established in the 1992 British Open by Nick Faldo at Muirfield, and tied by Brandt Snedeker at the 2012 Open Championship at Royal Lytham.
His 6-stroke advantage after two rounds tied the record set in 2000 by Tiger Woods at Pebble Beach and equaled by McIlroy in 2011. Kaymer is the sixth player to record double-digits under par at a U.S. Open, and the second to do it as early as the second round.
Kaymer started his round on the back nine and birdied 10, 13, 15, 3, and 5 to get to 10-under. He admitted he got "a little bit tired" down the stretch but saved par at Nos. 6 and 7 after hitting his approach shots into greenside bunkers.
The Open setup, which includes wider fairways and no rough, surely agrees with Kaymer.
"Usually at the U.S. Open, you know coming in it's going to be tight fairways, thick rough, fast greens," he said. "and this week it's a little bit different. I think for us Europeans, especially the guys from the U.K., we're more used to playing these golf courses than [those] with thick rough or long holes with tight fairways.
"So, I think it favors a little bit the European players."
It will be an uphill battle for those chasing Kaymer. Todd, whose profile has risen sharply since his win last month at the Byron Nelson Classic, fired a 67 for a 136 total and will play in the final pairing Saturday with Kaymer.
Snedeker carded a 68 to tie Kevin Na (69) at 137, and five players, including Bradley, were at 138. McIlroy had a 68, leaving him nine shots behind , and world No. 1 Adam Scott was 10 shots back after a 67.
Like his fellow challengers, Todd knows he will have his hands full.
"Kaymer's performance has been incredible," he said. "He's playing a brand of golf we haven't seen in a long time, since maybe Tiger. He might need to come back. I don't think there's too much opportunity to shoot 6- or 8-under on the weekend if he were to get a couple more [under par]. We're going to go out and do our best."