“I’m very happy with the way I’m swinging it, happy with the way I am hitting it,” McIlroy said after his round.

His 131 was a shot better than Ricky Barnes’s record, set in 2009 at Bethpage.

“I don’t know what to say,” McIlroy said when asked about the 36-hole record. “I’ve played two really good rounds of golf, but I know I have to play another two really good rounds of golf if I want to win this tournament, so that’s all I can really think about.

With birdies at 16 and 17, McIlroy also became the first golfer to get to 13-under at the Open — breaking the record of 12-under held by Tiger Woods and Gil Morgan.

“I feel very comfortable on this golf course, and there’s no real keys to how I’ve shot so well or went so low,” McIlroy said. “It’s just I just keep trying to hit it in the fairway and hit it on the green and try and hole a few putts, and I’ve been able to do that.”

McIlroy missed the fairway on 18, hitting it into the gallery, and then knocked his second shot into the lake left of the green. He made double bogey, but still leads Y.E. Yang, set to tee off at 1:35 p.m., by eight strokes.

Playing partner Phil Mickelson finished with a double bogey on 18 as well, turning in a 2-under 72 to follow up his disappointing first-round 74. The five-time U.S. Open runner-up was impressed with McIlroy, though.

“He’s striking it flawlessly and putted great on the greens,” Mickelson said. “His first two rounds were very impressive.”

The rising star has some experience leading majors, but has yet to close one out. He gave up a four-shot lead going into the final round of the Masters, shooting 80, and was unable to capi­tal­ize on an opening-round 63 at St. Andrews in last year’s British Open.

“Every time I get myself in a position to win, I get more and more comfortable,” McIlroy told ESPN. “I felt very much at ease today.”