Rory McIlroy is back on the course at the U.S. Open, showing no early signs of letting up.

In fact, he's increasing his lead.

Playing in calm conditions on a layout drenched by overnight rain, the 22-year-old from Northern Ireland opened Friday's round by hitting the first four greens in regulation and making three pars and a birdie to move to 7 under. That put him four shots ahead of Y.E. Yang.

McIlroy shot 6-under 65 to open the tournament Thursday. His three-shot lead after the first day was the biggest opening-round cushion at the U.S. Open in 35 years.

Charl Schwartzel, who won the Masters after McIlroy's collapse in the final round, started his day tied for second but made bogey on No. 3 to fall to 2 under — five behind McIlroy. Yang had an afternoon tee time.

Sergio Garcia and Kyung-tae Kim were in a group of six players who finished the first round a 2 under, but neither had gained on McIlroy midway through the first nine. Robert Garrigus and John Senden each made early birdies to join the large group at 2 under.

Conditions couldn't get much better for a U.S. Open, at least in the morning. Soft greens and forgiving rough were taking some of the bite out of Congressional, a monster course at more than 7,500 yards. McIlroy's first tee shot went slightly left into that rough but he had no problem wedging it out and onto the front of the green.

Counting Thursday's round, he has now hit 21 of 22 greens in regulation for the tournament.

"It doesn't feel like a typical U.S. Open, for some reason," McIlroy said after Thursday's play. "The golf course is going to get harder and it's going to get firmer and it's going to get trickier, but I still feel that it's very playable and fair. If you don't hit a fairway, you've still got a chance to hit it on the green and give yourself a chance for birdie."

British Open champion Louis Oosthuizen and American Ryan Palmer were in the large group at 2 under, hoping they could make up some ground in the afternoon, when they tee off.

The big question is whether McIlroy will still be in sight by then. He knows this is only the beginning.

"Well, there's definitely no relief in it," he said. "It's always nice to shoot a good first round at any tournament, let alone a major. But no relief. I know I'm playing well. I know this golf course."

McIlroy headed back out in a threesome with Phil Mickelson and Dustin Johnson.

Playing on his 41st birthday Thursday, Mickelson was wild from start to finish. Looking to improve on a 3-over 74 that could have been much worse, Mickelson started the second round with four straight pars. But on this day that meant he lost ground to McIlroy, whose 65 followed a first-round 65 at the Masters this year and a 63 at last year's opening round of the British Open, tying the major single-round scoring record.

Johnson bogeyed the fourth hole to drop to 5 over.

Also in need of a turnaround were the world's top three players. Luke Donald (74), Lee Westwood (75) and Martin Kaymer (74) combined for 17 bogeys and one double. They had afternoon tee times and will know where McIlroy stands before they take the course.

"I don't know if it says that I've just got a very short memory or, I don't know," McIlroy said in attempting to explain his strong first round. "I took the experience from Augusta, and I learned a lot from it. But I feel like these good starts in the majors are very much down to how I prepare for them."