Rory McIlroy off to a flyer on day one of US Open

A three-under-par 67 left McIlroy two shots off the lead held by Justin Thomas, with McIlroy's former Ryder Cup partner – and fellow new father – Thomas Pieters alongside Matthew Wolff and Patrick Reed on four under par.

Former Masters champion Reed and fellow American Will Zalatoris both made holes-in-one on the seventh and Zalatoris amazingly almost made another ace on the 13th when his tee shot hit the middle of the pin but stayed out.

Lee Westwood and Louis Oosthuizen were alongside McIlroy on three under, but world number one and FedEx Cup winner Dustin Johnson struggled to a 73.

McIlroy had spoken on Tuesday about the need for a good opening round as he looks to claim a first major title since the 2014 US PGA Championship.

In his last eight major starts, the former world number one was a total of 16 over par in the first round, compared to a combined 23 under in rounds two, three and four.

"First round of a major you're always anxious to play well and maybe I've overthought it at times," McIlroy said after his lowest opening round in the US Open since 2011 at Congressional, where he went on to win by eight shots.

"I just went out today and just took what was given to me a little more relaxed and played really nicely.

"I think at a US Open if you can get off to a good start, you're not chasing as much. And when you chase on US Open golf courses, that's when you can start to make mistakes and compound your errors."

Starting on the back nine, McIlroy birdied the 10th, 13th and 18th to be out in 32 and rebounded from a three-putt bogey on the first with a third two of the day on the difficult third.

McIlroy looked set to pick up another birdie after driving the green on the short par-four sixth, but three-putted from 40 feet for a disappointing par.

"There was a couple other chances I let slip by so there was chances there to maybe sneak another two or three out of the round," McIlroy added. "But at the same time, 67 here is always going to be a good score.

"Some courses you show up, you don't really have to work that hard for a 67, where here you do. So it's a little more gratifying."

Thomas carded six birdies and a solitary bogey in his 65, the world number three outscoring playing partner Tiger Woods by eight shots.

"It's one of the best rounds I've played in a while tee to green," Thomas said. "There are a couple things here and there that definitely could have been better, but I made sure all of my misses were in the right spot, and that's what you have to do at a US Open.

"It's helpful with three days left, but it's not even remotely close to being over. As great of a round and fun as it was, it's over with now and I need to get over it because I got 54 more holes to try to play well and shoot some good scores."

Woods, who missed his first cut in 38 majors as a professional at Winged Foot in 2006 following a nine-week lay-off after the death of his father, recovered from early bogeys to be level par after 16, only to bogey the 17th and take a double-bogey six on the last after duffing a pitch from short of the green.

American amateur Davis Thompson had been the early pacesetter after playing the first 11 holes in four under, but three late bogeys meant the 21-year-old had to settle for an opening 69.

England's Matt Wallace battled back from two over par after three holes to card a level-par 70, but US PGA winner Collin Morikawa returned a 76 and former Masters champion Danny Willett struggled to a 77.