San Francisco -Tiger Woods got his bid to win a fourth US Open title, four years after he won his last major, off to a strong start at San Francisco's Olympic Club on Thursday.
The 14-time major winner looked comfortable and confident throughout his early morning round as he carded a one-under par 69, which left him near the top of the leaderboard.
Playing partner Phil Mickelson, however, struggled badly, losing a ball in the gnarled Monterey Cypress trees with his opening drive and never really settling into his game after that as he limped along to a six-over 76.
The final member of what was the day's glamour grouping, Masters champion Bubba Watson, fared even worse as he sprayed the ball off the tee en route to a horrendous 78.
With the earliest of the morning starters back in the clubhouse, only a handful of players in a field of 156 had managed to duck under par at any stage on the rolling par-70 course, rated to be one of the toughest in years to host the US Open.
Leading the way was 27-year-old US qualifier Michael Thompson who came in with a pace-setting, four-under 66.
Woods was coming off a win in his last tournament, The Memorial, but has struggled for consistency of late, best illustrated by a tie for 40th in the Masters in April - the worst performance of his professional career in the year's first major.
Starting from the ninth hole, the 36-year-old former world number one, found the first four fairways as he opened with five straight pars.
A bogey on the 14th was cancelled by a birdie on the par-five 17th where he holed from four feet as he went out in level par 36.
Woods then stayed steady through the Lake Course's feared opening six holes highlighted by back-to-back birdies at the fourth and fifth where he sunk putts from 10 feet and then 30 feet.
He dropped one though at the next after failing to get up and down from a bunker having pushed his approach shot, and parred his way in from there.
Clubhouse leader Thompson, a runner-up in the US Amateur Championship here in 2007, had seven birdies against three bogeys in his round of 66.
He and Woods were the only sub-par rounds at that stage, though out on the course, former USPGA champion David Toms was one under with two holes to play.
It was a tough learning experience for China's Andy Zhang, at 14 and 1/2 years old believed to be the youngest player to compete in the US Open.
He had a morale-sapping triple bogey-double bogey start and, when three more bogeys followed, he was already a distant eight-over through five holes.
The Beijing-born qualifier steadied the ship somewhat after that, but he remained at eight-over through 14 holes, leaving him languishing near the bottom of the leaderboard.
The top grouping in the afternoon at 13:29 (20:29 GMT) was an all British affair comprising the world top three golfers - Luke Donald, Rory McIlroy and Lee Westwood.
Ulsterman McIlroy was bidding to become the first player to successfully defend the US Open title since Curis Strange in 1989, while Donald and Westwood were again seeking to win their first majors after years of failure.