Sweden's Henrik Stenson carded his lowest score ever in a Major as he and Dustin Johnson set the pace on day one of the US Open Championship at Chambers Bay.
Seeking to become the fifth European winner in the last six years, Stenson birdied four of his last five holes for a five under par 65 to share the lead with American Johnson.
Dutchman Joost Luiten, Italy's Francesco Molinari, Scotland's Marc Warren and Masters Champion Jordan Spieth were three shots off the pace after rounds of 68, with the 51 year old duo of Colin Montgomerie and Miguel Angel Jimenez another stroke back alongside Phil Mickelson, who needs a first US Open win after six runners-up finishes to complete the career Grand Slam.
World Number One Rory McIlroy, meanwhile, struggled on the greens in an opening 72, the same score as defending champion Martin Kaymer.
Stenson’s caddie Gareth Lord injured his left wrist on Wednesday, but still managed to partner the 2013 Race to Dubai winner.
“Walking off the 16th he took the fall, both feet in the air, and got trapped with his wrist under the bag," Stenson said. "He's in a cast now. It might be broken or just torn ligaments.
“He’s not in a good place with the hand, but he managed to caddie and did a good job for me anyway. I had to caddie for him a little bit, as well.
“I was striking it nicely, which led to a lot of birdie opportunities for me.
“I felt like I was really keeping my patience and a level head out there and very focused on the things that I wanted to be focused on.
“I hit some beautiful putts and managed to slip a few in there. It was a good way to finish the day.
“One day out of four done, and we're right there with where we want to be. It's still a long journey until Sunday afternoon, of course, but a good start always helps.”
Johnson threatened to equal the lowest score in Major Championship history of 63 when he reached six under par with two holes to play.
However the 30 year old, who won the WGC-Cadillac Championship in March, miscued a chip on the par five eighth and bogeyed the ninth.
Like Stenson, Johnson is seeking his first Major title after shooting a closing 82 when leading into the final round of the US Open in 2010, as well as missing the play-off in the US PGA Championship months later after being penalised for grounding his club in a bunker on the 72nd hole.
Mickelson was three under par after 11 holes before bogeys on the 13th and 14th, but said: “I have no complaints. I’m under par in the first round of the US Open and I am pretty pleased.
“I thought it was a very fair test. The set-up was good but I think everyone in the field is going to struggle with three to eight-foot putts when they are downhill, because you can't hit it hard enough to hold the line and there is a lot of wiggle.”
Late in the day, Branden Grace and Shane Lowry defied a stiffening breeze to sign for rounds of 69, meaning a total of nine European Tour Members finished the first day under par in Seattle.
