In one of those can't-miss moments in sports, thousands of fans covered every inch of space on the hill behind the 10th green at Congressional. They spilled onto the clubhouse veranda, pressed their faces against the windows and lined up against the balcony railing to watch Rory McIlroy deliver a performance never before seen in the U.S. Open.

"It was Tiger Woods of 11 years ago," Ian Poulter said.

In some respects, it was even better.

McIlroy, the sympathetic figure at the Masters, was as close to perfect as golf allows Friday during a stunning assault on the record book. The 22-year-old from Northern Ireland became the first player in the 111-year history of the U.S. Open to reach 13-under par, and despite a double bogey into the water on the final hole, his 5-under 66 was enough set the 36-hole scoring record at 131.

He had a six-shot lead over former PGA champion Y.E. Yang (69), matching the U.S. Open record set by Woods in 2000 at Pebble Beach for the largest margin at the halfway point.

McIlroy went 17 holes without missing a green. He went 35 holes without making a bogey.

"It's very near the best I can play," he said.

Not since Woods destroyed his competition at Pebble Beach in 2000 for a record 15-shot victory has anyone made golf look this easy, at least for two rounds.

As if playing under complete control were not enough, McIlroy hit a wedge from 114 yards some 15 feet behind the flag on No. 8, then watched it roll down a slope and into the cup for eagle. The only time he came close to making bogey was on the par-4 11th, when he blasted out of a bunker to 8 feet and made the putt.

He tied the U.S. Open record of 12 under – previously held by Woods in 2000 and Gil Morgan in 1992, both at Pebble Beach – on the par-5 16th with a 4-iron from 223 yards that settled 8 feet from the cup.

"I told him, 'I don't think you'll see a better golf shot,'" his caddie, J.P. Fitzgerald, said.

Then came the 17th, when McIlroy hit 7-iron from 175 yards that covered the flag, barely cleared the bunker and left him 15 feet below the hole for yet another birdie to go to 13 under.

That number just isn't seen on leaderboards at the U.S. Open.

"It's crazy, isn't it?" Steve Stricker. "Pretty incredible what he's done so far."

McIlroy knows better than to start the celebration before Sunday. He was buoyed by support coming into the U.S. Open because of the calamity at Augusta National from two months ago, when he led by four shots going into the final round of the Masters and shot 80, the kind of collapse that isn't easily forgotten.

"It's been two very, very good days of golf," McIlroy said. "I put myself in a great position going into the weekend. But I know more than probably anyone else what can happen. So I've got to stay really focused and try and finish this thing off."