Pebble Beach: Canadian Mike Weir holed out from just off the green to birdie the par-four 16th and grab an early one-shot lead at the US Open while Phil Mickelson struggled.
Left-hander Weir pumped his left fist in celebration after his ball disappeared into the cup following a delicate flop shot from the rough, lifting him to three under on a relatively calm, sun-splashed day at Pebble Beach.
South Korean KJ Choi, after 16 holes, and Britain`s Ian Poulter, after 13, were at two under in the first round with Spaniard Rafael Cabrera-Bello and American David Toms a further stroke back.
Cabrera-Bello held the clubhouse lead after opening with a 70 while 2001 US PGA champion Toms had five holes remaining.
Although the early starters had to contend with only light breezes on the spectacular coastal layout, Pebble`s notoriously small greens posed continual problems on a course running fast and firm.
World number two Mickelson, in the eyes of many the best player in the game over the last nine months and regarded by several leading bookmakers as the tournament favourite, was among several players to suffer.
The US Masters champion was four over after 14 holes, having limped to the turn with three successive bogeys from the 16th after starting at the 10th.
His tee shot at the par-three 17th ended up on the beach and his second shot at the par-five 18th, struck from behind two trees on the fairway, landed on a seawall before his ball bounced sideways into the ocean.
Triple champion Tiger Woods, who romped to a 15-stroke victory when the US Open was last held at this venue in 2000, was among the late starters.
The world number one was scheduled to tee off from the first hole in a high-profile grouping with third-ranked Briton Lee Westwood and double US Open winner Ernie Els of South Africa.
Although Woods is comfortably the best player of his generation, he has several question marks hovering over his form this week.
He has played in only four PGA Tour events this season, with a best finish of joint fourth at the Masters in April and a missed cut at Quail Hollow, after he took nearly five months off following revelations of his marital infidelity.
The 34-year-old has struggled for accuracy off the tee while battling a lingering neck injury and he recently parted company with his long-time swing coach Hank Haney.