Adam Hadwin of Canada fired a 4-under-par 66 late on Thursday to secure the first-round lead in the US Open at The Country Club in Brookline, Massachusetts.
Hadwin moved ahead of Rory McIlroy, who shared the lead at the conclusion of his round before ending up in a five-way tie for second place at 3-under 67.
McIlroy, a four-time major champion from Northern Ireland, was tied with Joel Dahmen, England's Callum Tarren, David Lingmerth of Sweden and MJ Daffue of SA. England's Matt Fitzpatrick and Justin Rose, as well as Dustin Johnson, Hayden Buckley, Matthew NeSmith, Brian Harman and Aaron Wise were tied for seventh at 2-under 68.
Hadwin compiled five birdies in a six-hole stretch to make the turn at 4-under 31. That included three straight birdies at numbers 7 to 9, with his second shot at the par-4 ninth rolling to inside three feet of the pin.
After a bogey at the par-4 12th, Hadwin recovered with a birdie at the par-4 13th to re-establish himself as the sole leader.
Hadwin, 34, earned his only PGA Tour victory in 2017. He has never finished inside the top 20 at a major.
McIlroy entered as the odds-on US Open favorite after he won the RBC Canadian Open on Sunday. He stayed hot, starting his day on the back nine with two birdies before holing back-to-back birdies at the seventh and eighth holes to reach 4 under.
But a tough shot from off the ninth green left him a long par putt he couldn't convert, and his only bogey of the round left him out of the outright lead at the end of the day.
"I wanted to try to shoot a round of golf on a really tough course without making a bogey," McIlroy said on the NBC broadcast.
"I achieved that for 17 holes and then didn't quite save par there at the last. But overall a really good day. Had some really good par savers. Hit the ball pretty well and it's a great start to the tournament."
Adam Hadwin leads US Open, Rory McIlroy one shot back
Adam Hadwin of Canada fired a 4-under-par 66 late on Thursday to secure the first-round lead in the US Open at The Country Club in Brookline, Massachusetts.
Hadwin moved ahead of Rory McIlroy, who shared the lead at the conclusion of his round before ending up in a five-way tie for second place at 3-under 67.
McIlroy, a four-time major champion from Northern Ireland, was tied with Joel Dahmen, England's Callum Tarren, David Lingmerth of Sweden and MJ Daffue of SA. England's Matt Fitzpatrick and Justin Rose, as well as Dustin Johnson, Hayden Buckley, Matthew NeSmith, Brian Harman and Aaron Wise were tied for seventh at 2-under 68.
Hadwin compiled five birdies in a six-hole stretch to make the turn at 4-under 31. That included three straight birdies at numbers 7 to 9, with his second shot at the par-4 ninth rolling to inside three feet of the pin.
After a bogey at the par-4 12th, Hadwin recovered with a birdie at the par-4 13th to re-establish himself as the sole leader.
Hadwin, 34, earned his only PGA Tour victory in 2017. He has never finished inside the top 20 at a major.
McIlroy entered as the odds-on US Open favorite after he won the RBC Canadian Open on Sunday. He stayed hot, starting his day on the back nine with two birdies before holing back-to-back birdies at the seventh and eighth holes to reach 4 under.
But a tough shot from off the ninth green left him a long par putt he couldn't convert, and his only bogey of the round left him out of the outright lead at the end of the day.
"I wanted to try to shoot a round of golf on a really tough course without making a bogey," McIlroy said on the NBC broadcast.
"I achieved that for 17 holes and then didn't quite save par there at the last. But overall a really good day. Had some really good par savers. Hit the ball pretty well and it's a great start to the tournament."
Dahmen, 34, started on the back nine and heated up late, with birdies on three of his final five holes to join McIlroy and the early co-leaders. Dahmen made birdie at three of the four par 3s.
Tarren was even through 15 holes before going birdie-eagle at the par-4 seventh and par-5 eighth to shoot up the leaderboard. Tarren's second shot at No 8 nestled inside five feet for an easy eagle. Ranked No 445 in the world, the 32-year-old has never won on the PGA Tour or DP World Tour.
Lingmerth is a PGA Tour veteran who won his only career title in 2015. He entered the week ranked even lower than Tarren - No 592 in the world. He stayed bogey-free with three birdies.
Johnson, the 2016 US. Open champ, played in the late wave in his first appearance since leaving the PGA Tour for LIV Golf. He carded four birdies to counteract two bogeys.
Rose, the 2013 US Open winner, started on the back nine and posted a colourful card featuring five birdies and three bogeys. He settled in from there, with one more birdie and bogey on the front nine.
Defending champion Jon Rahm of Spain, two-time major winner Collin Morikawa, PGA Championship winner Justin Thomas, Will Zalatoris, Max Homa and Australia's Adam Scott were part of a large group tied at 1-under 69.
Rahm made a wild birdie at No 18 to finish his round. After his drive missed badly left, he was granted a free drop from behind a media tower after someone ran off with his ball. He found the edge of the green and drained a 21-footer for birdie.
"I'm pretty sure I know who it was," Rahm said with a grin.
"I recognised the two kids who were running the opposite way with a smile on their faces. I am 100% sure I saw the two kids who stole it."
World No 1 Scottie Scheffler, Xander Schauffele, Patrick Reed, Norway's Viktor Hovland and Japan's Hideki Matsuyama shot even-par 70. Bryson DeChambeau posted a 1-over 71, and Jordan Spieth, Patrick Cantlay and Australian Cameron Smith opened with rounds of 2-over 72.
Phil Mickelson was tied for 144th after an 8-over 78. After taking a three-month pause from the game and eventually choosing to join LIV Golf, he was competing on American soil for the first time since January. Mickelson had five bogeys, two double bogeys and just one birdie on his card.
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