Two days after stressing the need for a fast start in his pursuit of a fifth Major title, McIlroy’s prayers were answered at a surprisingly benign Winged Foot Golf Club.
Australia’s Geoff Ogilvy shot five over par to win the last US Open at the venue in 2006, while American Hale Irwin was seven over in surviving the so-called “Massacre at Winged Foot” in 1974.
A three under par 67 left McIlroy two shots off the lead held by Thomas, with McIlroy’s former Ryder Cup partner – and fellow new parent – 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.
-5 Thomas— The European Tour (@EuropeanTour) September 17, 2020
After 18 holes. #USOpen
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 U.S. 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 U.S. 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.”
Pieters made birdies on the second, ninth and 11th but bogeyed the 12th after a wayward drive on the par five.
The 28-year-old produced a strong finish, however, birdieing the 17th from three feet and then rolling in a 13-footer for a gain at the last.
“I drove it really nicely and I had some really deep ones, so left myself some really short wedges into long par fours, which helps,” he said.
“The fairways are really firm, so that's going to be key to hit the fairways the rest of the week.
“Back nine I struggled a little bit off the tee, and I was kind of having to make par from some positions, and I did, but can't be doing that all week, so got to just tidy that up. Overall very happy.”
Starting on the back nine, McIlroy birdied the tenth, 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.”