Dustin Johnson and Henrik Stenson moved into a tie for the early US Open lead on Thursday while Phil Mickelson made an encouraging start in his bid for a career grand slam of the four majors.
Long-hitting Johnson took advantage of calm conditions on a firm and fast-running Chambers Bay layout as he fired a five-under-par 65 in the first round of the year's second major, which is being played for the first time in the Pacific Northwest.
The 30-year-old American piled up six birdies and a lone bogey to finish level with Swede Henrik Stenson, who birdied four of his last five holes at the British Open-style venue.
They were one stroke ahead of American Patrick Reed with half the field back in the clubhouse, while American Matt Kuchar trailed by two.
"I hit the ball really well ... had a lot of good looks at birdie all day," Johnson, who like Stenson is seeking a first major title, told reporters.
"It's firm but you could control your golf ball, for sure. Today I controlled my ball very well. The confidence is definitely there. I feel really good about where I'm at and going into tomorrow."
Stenson joined Johnson at the top after draining a 20-foot birdie putt on the 18th for a homeward nine of four-under 31.
"It was a good day," said the Swedish world number six. "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. I hit some beautiful putts and managed to slip a few in there. It was a good way to finish the day."
Mickelson, who is yearning to complete a career grand slam of the four majors by winning his first US Open, was "very pleased" after carding a 69 that included four birdies and three bogeys.
"I hit a lot of good shots today," Mickelson, a runner-up at the US Open a record six times, said after hitting nine of 14 fairways and totalling 31 putts. "I shot under par the first day of the US Open.
"The first round was the round I was going to be most nervous at, getting started. You don't want to have to fight to come back all the time. You want to get off to a solid start around par.
"I'm very pleased with the way the round went."
It was an average morning for Northern Ireland's world number one Rory McIlroy. Seeking his fifth major victory, he birdied his second hole but never got into top gear to return a 72.
Masters champion Jordan Spieth was among the late starters, and teed off with 2013 champion Justin Rose of England and Australian Jason Day in one of the most eye-catching trios of the day.
Spieth is seeking his second major crown after clinching his first in sensational fashion at the Masters in April when he completed a wire-to-wire victory by four shots to match Tiger Woods's tournament record low for 72 holes.
Woods, who has been struggling for form and won the most recent of his 14 major titles at the 2008 US Open, was also among the late starters.
