Martin Kaymer has a six-shot lead after two rounds of the U.S. Open. (Sam Greenwood/Getty Images)

Perfect golf is boring golf, unless you’re the one who’s playing it.

Then the game feels transcendent, like performing in total-awareness slow motion. You’re in control of body and emotions, club and ball, the whole green world your friend and accomplice, at least for the time that such perfection lasts. Almost every avid golfer, including those with a high handicap, has felt such perfect interludes, if only for a day at most. So it’s not just Martin Kaymer, who leads the U.S. Open here by a record-tying six shots after two rounds, who knows this blissful feeling of ideal golf.

But few men have ever visited the realm where the 29-year-old German temporarily resides. In all the major golf tournaments ever played, only one man ever shot a score as low as 130 in the first two rounds — Nick Faldo at the British Open in ’92. Kaymer has matched him. In U.S. Opens here in ’99 and ’05, nobody shot a score as low as 65. Kaymer just went 65-65.

“It gets boring, the words that I use, but there is not much to say,” Kaymer said. “Just very good golf. Not much to say about it.”

Except that it is amazing to see a man play his final nine holes Thursday and his first 14 holes Friday in 9 under par with no bogeys and almost no interaction whatsoever with a course that is traumatizing almost everyone else. In that span of 23 holes, Kaymer was barely playing Pinehurst No. 2 at all. He was simply walking “down the watering system,” and from there every course looks the same.

“It was so fun to watch him,” said playing partner Keegan Bradley, whose own 69-69 would normally have seemed special. “It was pretty awesome to see him hit every fairway, every green and make every putt for two days. He’s as dialed in as I’ve ever seen.”

Without “perfect golf,” without the lure and hope of it, there would probably be no golf at all. Who’d put up with the tormenting game otherwise? We all have our version of the same experience: “I’ve got it. And it’s so simple.” Then the next time we play some little thing is different, which leads to a slight compensation that tilts the axis of perfection just enough that, once again, we are just us. Ugh.

Something similar applies to the greats. Adam Scott, ranked No. 1 in the world, was asked, “How long does ‘perfect golf’ last?” “For a couple of holes,” he said, then added, seriously, “a couple of times maybe I’ve gone 17 holes.”

“I don’t know if I’ve done it for more than five or six holes in a row. That’s how tough this game is,” veteran Steve Stricker said. “Something always creeps up and gets you, especially at an Open.”

Will golf — or just human imperfection — creep up on Kaymer this weekend? And how will he react when it does? “It’s very difficult to play four rounds of great golf. I’m sure there is going to be a day when you struggle,” Kaymer said. “Accept a couple bogeys here and there. Don’t get mad at yourself.”

Anything else?

“You don’t compare,” he said. “The comparing is the biggest mistake you can do, especially if you are playing . . . ”

Out of your mind?

“The last two rounds . . . were very exceptional, so comparing is never really good.”

Kaymer is a perfect case study of a truly fine player — but a far from invincible one — who now has the kind of lead that, to the casual fan, seems almost impossible to blow. Golfers know better.

The lean 29-year-old, ranked 28th in the world, won the ’10 PGA Championship. Just last month he opened with a 63, then won wire-to-wire at the Players Championship. Kaymer also sank the clutch six-foot putt to clinch the ’12 Ryder Cup for Europe in a huge upset. So he has a serious résumé.

But he also has a memory. He has played in 18 tournaments this season, a total of 60 rounds. In all of those 1,080 holes combined he is only 6-under par. That’s all — just 6. Yet on the toughest of tests, he’s 10 under — only the sixth player ever to go that low at any point in a U.S. Open.

Major tournament golf appeals to fans so intensely because brutal courses reveal how similar the best players are — in their emotional and technical disintegration under pressure — to the rest of us.

The weekend at this Open will be about how Kaymer copes with a gradual but inevitable falling away from his state of grace.

Those testing times may already have begun. On Kaymer’s last four holes he shook first his left hand, then his right after ground-pounding iron shots. An injury? “It’s nothing,” he said. “I just play too much golf.” In other words, it is something. His hands hurt enough to rub and shake.

Kaymer’s alternate explanation for needing to save par from greenside bunkers on three of his last four holes was “I was just a little tired” from jet lag coming from Europe and the heat here. But it may also have been the first evidence of perfect golf seeping away.

Like all pro golfers, Kaymer has his demons. In the past he has been bothered by what’s said about him in social media sites. He was once briefly No. 1 in the world but tried to change his swing to improve his game even further and ended up smashing the beautiful thing. That wasted ’11 and ’12. Right up until his win at the Players he still would see golf Web sites that annoyed him. “ ‘Is he a one-hit wonder? Will he ever come back?’” said Kaymer. “Deep inside I never doubted. . . . It is just [expletive].”

If Kaymer’s nervous system has one ally, it is the timing of Germany’s first World Cup game.

“Golf is a little bit of a side sport [in Germany]. It’s not that important,” Kaymer said. “I’m glad that Germany starts on Monday so maybe I get little things in the newspaper about me.”

What if he wins?

“It will last probably until Monday, 12 o’clock,” Kaymer said, “and then that’s it.”

In Germany, perhaps. But in Pinehurst and the rest of the golf world, what Kaymer does the next two days may be remembered a very long time.