Rory McIlroy was aiming to finish his day in red numbers despite opening with a two over 72 on his US Open debut.

The Holywood ace, 20, could have shot a high number after slumping to four over par after 12 holes in perfect conditions at Bethpage Black.

But he grabbed a hat-trick of birdies coming home to limit the damage and hoped to pick up at least three shots as set off to play at least nine holes of his second round before bad light stopped play.

As Darren Clarke hit a four over par 74, McIlroy said: "It was looking like a 76 or a 77 but those three birdies got me back a little bit. I was disappointed to bogey seven from the middle of the fairway but a 72 out there is a pretty solid effort."

After opening with a bogey five at the 10th, he bogeyed the 12th as well to drop to two over par before reducing to the 605 yard 13th to two massive hits and two putts for a welcome birdie.

Just when he was cruising, the Holywood hotshot double bogeyed the first and bogeyed the second to slump to four over par.

But he hit back with three birdies in a row, two putting the par five fourth before hitting superb shots close at the fifth and sixth.

He said: "I hit it well on the first but had one of those US Open lies and should have take my medicine and chipped out. I ended up with a double.

"But one of the biggest points of the round was making a bogey five at the second because it was looking like a six or a seven but I got up and down from the rough from about 70 yards.

"That kept me going and then the three birdies in a row got me back into it. You just have to be patient. I drove the ball really well and hit a few bad iron shots."

Clarke got off to a nightmare start when he double bogeyed the 10th to slip to two over straight away.

He dropped another shot at the tough 15th but while he birdied the 18th to turn in two over he shed two more shots on the back nine with bogeys at the fourth and fifth forcing him to settle for a 74 that left him in the bottom half of the field.

That left him 10 shots adrift of former Masters champion Mike Weir, who came with a shot of equalling the lowest round in US Open history when he fired a six under par 64.

The Canadian was on course to break the magical 63 barrier when he got to six under with four to play but he double bogeyed the sixth - his 15th - before finishing with two birdies and a two shot lead over Swedish qualifier Peter Hanson (66).

Before setting off for his second round, McIlroy said: "You see Mike Weir got to six and then fell back to four but it shows that it can be done. If I can end today in red numbers then it’ll be a good days work.

"My game is in good shape. I was pleased the way I hit it and we have definitely got the good side of the draw and you have to take advantage of that.

"The front nine is supposed to be the one where you can make a score so I want to try and go out there and take advantage tad get it to even par or one under for the tournament - that would be a great effort.”

Former Open champions David Duval and Todd Hamilton were three shots off the pace after 67s with last year's runner up Rocco Mediate on two under after a 68.