There’s only one number that matters to Rory - first on Sunday night. But after hitting 17 greens and nine of 14 fairways in a superb opening 65, the 22-year old Ulsterman has given the field a major headache entering today’s second round.

His brilliant, bogey free effort gave him the biggest first round lead at a US Open for 35 years - three strokes over YE Yang and Masters champion Charl Schwartzel. But as Padraig Harrington pointed out after his round, the USGA will want revenge.

“If somebody gets  starts rolling to 6, 7, 8, 10 under par, they’re going to make it tougher,” Harrington said.

Second round hole locations at Congressional todayHeavy overnight rain has left Congressional soft and vulnerable so it was no surprise to see the pins set in ultra tough positions today with a back left hole location at the 18th with the only middle pins at the back of greens (see pic).

McIlroy won’t be too worried about that if he strikes the ball as superbly well as he did on Thursday afternoon, when he outscored playing partners Phil Mickelson  and Dustin Johnson by nine and 10 strokes respectively.

“I don’t think conditions were that easy,” McIlroy said. “You know, there was a little bit of a breeze out there, and the greens were getting pretty firm.  A few of the greens around the holes were getting pretty chewed up, as well.  It was tricky out there, but I just managed to keep the ball in the fairway and find a lot of greens, and that was basically how I shot that score.”

McIlroy’s performance was all the more remarkable considering his previous round in a major was that infamous, closing 80 at Augusta, where he led by four strokes entering the final round.

It was the third time in the last four majors that McIlroy has held the first round lead and his task now is to press on and win. As he said after Augusta, his biggest mistake in the final round was trying to defend his lead instead of just playing his normal game.

“I don’t know if it says that I’ve just got a very short memory 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 my preparation and how I prepare for them.  But yeah, I mean, you can’t  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 best you can prepare and how you can get yourself around the golf course.”

Rory McIlroy plays his approach to the fourth in the opening round of the 111th US Open. It was one of the few times he failed to find the fairway. Credit: www.golffile.ieAsked what he’d learned that day, McIlroy said: “Just being so tentative and trying to keep ahead of the field instead of playing a free-flowing game like I usually do.  That’s one of the big differences.”

“The first three days I played aggressively.  I played smartly but I played aggressively to my targets and aggressively to the spots I wanted to hit it.  And then going into the Sunday, I started to play defensively, and that’s when things can go wrong.

“Yeah, again, this week it’s about being aggressive to the spots  a lot of it this week, there’s 200 yard plates and 150 yard plates on the fairway.  A lot of holes I’m just trying to hit it to the 150 spot off the tee, and then I’m playing my iron shot in from there, so it’s being aggressive to the target that you have.”

McIlroy began his back nine by holing this putt for a birdie at Congressional’s first hole. Credit: www.golffile.ieGiven the penal pin positions, McIlroy can’t afford to be too aggressive today. But after following an opening 63 with an 80 at St Andrews in last year’s Open, he knows the definition of a good score.

“I learned a lot from it.  It was my first experience at leading a major and leading it going into the second round.  You know, the weather obviously wasn’t very kind to me.  But I just learned that it’s a long way to go, even after that 63.  It’s hard to put thoughts out of your head about going on and winning and everything, but you’ve got to really stay in the present and stay in the moment. 

“And I felt like I handled the second round at Augusta this year a lot better than I handled the second round at St. Andrews last year.”

It’s hard not to expect McIlroy to play well again today on a course that appears to fit his game like a handmade glove.

“I don’t think I should be trying to do anything differently tomorrow than I did today,” he said. “I didn’t go out there thinking about shooting any sort of a score.  I just went out there to try and play really good golf, stick to my game plan, stick to the clubs I’m going to hit off tees and all that.”