There was a moment Friday morning when Rory McIlroy was, inarguably, lucky. He stood 114 yards from the eighth pin at Congressional Country Club. He felt a bit awkward, in between clubs. Yet he committed to a pitching wedge, tossed it some 20 feet past the hole, then watched it roll back slowly, down a slope.

That it went in for an eagle 2 amounted to McIlroy piling on the entire field. Standing in the fairway, he threw his arms in the air. The gallery, already filling every seat and five deep around every available rope, thundered its approval. The group ahead — Steve Stricker, David Toms and Retief Goosen — peered over from the ninth tee to confirm what they already knew. Yep, the kid did it again.

In authoring a historic, commanding performance over the first two rounds of the U.S. Open, McIlroy has scarcely needed good fortune. He followed his splendid opening 6-under-par 65 with a 66 Friday that was, in some ways, even more impressive, and he owes his six-shot lead over South Korea’s Y.E. Yang to one thing: his own sublime ability, which currently may be unsurpassed in golf.

“I don’t really know what to say,” McIlroy said.

A ridiculous list of numbers — numbers reminiscent of the Open’s most notable absentee, Tiger Woods — says it for him. McIlroy’s two-day total of 131 — which is 11 under on Congressional’s 7,574-yard layout — is the lowest 36-hole score in the 111-tournament history of the Open. When McIlroy’s eagle trickled in at 8, he got to 10 under for the event — double digits under par faster than anyone else, in just 26 holes. The next quickest: Gil Morgan, who needed 39 holes to reach 10 under in 1992. The only other man to lead the Open by six shots at the midway point: Woods in 2000 at Pebble Beach. (Note: The third round is underway. Click here for tee-times and here for live scoring.)

“It’s funny to me,” McIlroy said. “You know, it feels quite simple.”

Thus, the weekend will be either coronation or, frankly, catastrophe. McIlroy, 22, can’t enter a discussion about his play in major championships without a mention of a place (Augusta National), a tournament (the Masters) and a final-round score (80) that, fairly or not, define his fledgling career.

Given his domination of the field here — he had the lowest score of the day both Thursday and Friday, he has missed just four of 36 greens, and for the first 35 holes he made no score worse than par — every aspect of that round and its aftermath has been dissected.

“We had a good discussion,” said his caddie, J.P. Fitzgerald. “It’s private. It stays in-house. But we both had things we had to improve on.”

Previously this week, McIlroy said he needed to stay aggressive when he had the lead, that he became tentative with his four-shot advantage on Sunday at the Masters. Friday, he added another wrinkle.

“I needed to be a little more cocky, a little more arrogant on the golf course, and think a little bit more about myself, which I’ve tried to incorporate a little bit — just on the golf course,” McIlroy said. “I just try and have a bit of an attitude.”

That attitude, at least on Friday, was to take his large lead — which was seven shots after the eagle — and make it grow. He made a superb par save at 11 from a bunker and came to the par-4 14th, which Friday played at 454 yards. McIlroy then floated a fantastic 6-iron to six feet for the birdie that got him to 11 under.

“I told him on 14 I didn’t think I’d see a better iron shot,” Fitzgerald said. “Then he hit the one at 16.”

On that par 5, McIlroy sat in the middle of the fairway, 223 yards from the flag. Fitzgerald handed him a 4-iron, and he unleashed yet another glorious swing that should have been captured in a still shot, from behind, for posterity. The ball settled 10 feet from the pin. That he missed the eagle putt? No matter.

“I think everybody would agree he’s probably got more talent in his pinkie than I have in my whole body,” said Brandt Snedeker, nine shots back — and tied for third. “He is unbelievably talented. . . . He does everything well. I love watching him play because it’s a very classical, beautiful golf swing.”

That swing next laced a 7-iron just over a bunker to 15 feet at 17, and he rolled the putt right in. The galleries — worthy, at this point, of Woods in his prime — exploded for the first man ever to get to 13 under at the U.S. Open.

“That’s what you want,” said Mike Davis, executive director of the U.S. Golf Association. “You want to set up a course where if you hit good shots you’re rewarded. He did that. I think it’s great. It’s kind of like Tiger at Pebble Beach in 2000.”

That performance — when Woods tied the Open scoring record of 272, set a record of 12 under and won by an unprecedented 15 shots — remains unmatched. And on 18, McIlroy marred his Mona Lisa with a big, black mark. He missed the fairway left, tried to punch up short and right of the green, and hit it off the toe of the club — into the water.

After the resulting double bogey, McIlroy plucked the ball from the cup, and — in one motion, without looking — tossed it underhanded into the pond beside the green. As he walked across the bridge from the 18th green, past the massive grandstand in which not a soul sat silent, there was the first and only bit of frustration of McIlroy’s first two days. Whether the weekend would bring history — in a historic first major victory, or a historic collapse — he did not yet know.

“We’re only halfway there,” Fitzgerald said.

“I know more than probably anyone else what can happen,” McIlroy said.