UNIVERSITY PLACE, Washington — Dustin Johnson and Henrik Stenson set the first-round pace at the US Open Thursday on a day of remarkable highs and lows as Tiger Woods shot an 80, his fourth-worst score as a professional. American Johnson and Swede Stenson fired matching five-under-par 65s on a firm and fast-running Chambers Bay layout while Phil Mickelson made an encouraging start with a 69. The long-hitting Johnson piled up six birdies and a lone bogey to finish level with Stenson, who birdied four of his last five holes at the British Open-style venue in the year's second major, being played for the first time in the Pacific Northwest. They were one stroke ahead of American Patrick Reed, while Americans Matt Kuchar, Ben Martin and amateur Brian Campbell 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. 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 No. 6. “I was striking it nicely, which led to a lot of birdie opportunities for me. Mickelson, who is yearning to complete a career Grand Slam of the four majors by winning his first US Open, was “very pleased” after a round 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. “I shot under par the first day of the US Open.” It was an average morning for Northern Ireland's world No. 1 Rory McIlroy. Seeking his fifth major victory, he birdied his second hole but never got into top gear as he struggled on the greens to return a 72. “I need to find a rhythm in my stroke over the next three days, work a bit on the putting green,” said McIlroy. “Hopefully it will be better tomorrow.” Masters champion Jordan Spieth, who played in the more difficult conditions of the afternoon as the course firmed up, was delighted to open with a 68. “It was a good solid day,” said the 21-year-old Texan. “To shoot two under at the US Open, I would have signed for that before I started.” Woods, who has been struggling for form and won the most recent of his 14 major titles at the 2008 US Open, endured a nightmare day at Chambers Bay. Wayward off the tee, the former world No. 1 toiled away in bunkers and thick fescue rough before ending his round with a bogey at the par-five 18th where he cold-topped a three-wood from the middle of the fairway. — Reuters