RORY MCILROY IS becoming a master at these major championships. At least on Thursdays.

Showing no linger effects from a Sunday collapse at the Masters, the 22-year-old McIlroy made the toughest test in golf look like child’s play at Congressional with a six-under 65 to build the biggest 18-hole lead at the US Open in 35 years.

He missed only one green. He was the only player in the 156-man field without a single bogey. And just like that, McIlroy wound up atop the leaderboard after the opening round for the third time in the last four majors.

“It felt like quite a simple 65,” McIlroy said. “I didn’t do much wrong.”

The trouble has been finishing them off.

There were questions about how McIlroy would respond after the calamity of his most recent round in a major, when he squandered a four-shot lead at Augusta National with an 80 in the final round. He has been saying ever since that he got over that meltdown a week after the Masters. By the way he bounced back at the US Open, maybe it’s time for everyone to believe him.

“I don’t know if it says that I’ve got a short memory,” McIlroy said. “I took the experience from Augusta, and I learned a lot from it. But, yeah, I mean you’re going into the U.S. Open. You can’t be thinking about what’s happened before. You’ve got to just be thinking about this week, and how you can best prepare, and how you can get yourself around the golf course.”

He took a route unlike any other player on an overcast day with a few light showers just as he finished up his round.

McIlroy was three shots clear of former PGA champion YE Yang and Charl Schwartzel, the South African who captured the Masters two months ago at McIlroy’s expense.

“It’s a long way to go, but it’s nice to get yourself in contention,” Schwartzel said. “If you start falling too far behind on a tough golf course, things can get a little bit too far in front of you. You need to stay in there with a chance.”

British Open champion Louis Oosthuizen was at 69, joining a small group that included Sergio Garcia and Ryan Palmer, the lone American among the nine players who broke 70.

Phil Mickelson played alongside McIlroy, and it must have looked familiar. The last time the US Open came to Congressional in 1997, Mickelson played with Colin Montgomerie, who also shot 65.

Defending champion Graeme McDowell had a 70. He was happy with that.

“The game’s easy when you hit it straight and make every putt,” Mickelson said, referring to McIlroy. “It’s a wonderful game. No course is too tough when you hit like that. He played terrific. It was fun to watch — although I didn’t see much of it.”

The top three players in the world — Luke Donald, Lee Westwood and Martin Kaymer — combined to go 10-over par. Donald struggled with his accuracy and couldn’t cope with the thick rough and shot 74 despite his birdie-birdie start. Kaymer also had a 74, while Westwood staggered to a 75, his worst opening round at the U.S. Open in 10 years.