World number one Rory McIlroy has said that he needs to improve his putting, after an opening round of 72 left him seven shots off the lead at the US Open.

The Northern Irishman is on two-over par after day one, but insists that it could have been a lot better if his putting was at its best.

He told reporters: "I felt like I played well tee to green and gave myself a lot of looks but did not take advantage of the good shots I was hitting. There were a couple of misreads and a couple of bad strokes in there as well.

"It's hard to pick the line and trust it and then you start making tentative strokes and you are not getting a true roll on the ball. I need to work on that before tomorrow's round and see if I can figure something out."

Dustin Johnson and Henrik Stenson are currently the clubhouse leaders on five-under par.