First round leaderboard:
-2 S Micheel (US), P Casey (Eng), B de Jonge (Zim) -1 R Cabrera Bello (Spa), KJ Choi (Kor), M Weir (Can), I Poulter (Eng), A Cejka (Ger), R Ishikawa (Jpn)
Level L Donald (Eng), D Toms (US), G McDowell (NI), D Johnson (US)
Selected others: +1 R McGowan (Eng) +2 S Garcia (Sp) E Els (SA), MA Jimenez (Sp), M Richardson (Eng), P Harrington (Ire) +3 V Singh (Fij), L Westwood (Eng), T Woods (US), R Fisher (Eng) +4 R McIlroy (NI), O Wilson (Eng), A Cabrera (Arg), R Goosen (SA), P Mickelson (US) +5 S Dyson (Eng), S Khan (Eng) S Cink (US) +7 T Watson (US) +9 B Davis (Eng)
World number nine Casey is still chasing his maiden major title
England's Paul Casey will take a share of a one-shot lead into the second round of the US Open at Pebble Beach.
Casey shot a two-under 69 along with American Shaun Micheel and Zimbabwe's Brendon de Jonge on a testing but absorbing day in California.
Ian Poulter is in a chasing pack of six at one under, with Luke Donald and Graeme McDowell at level par.
Tiger Woods and Lee Westwood ended three over with Phil Mickelson another shot adrift after a four-over 75.
Despite relatively benign conditions and kind pin positions, the 156-man field struggled to tame the iconic course on the Monterey Peninsula with only nine players shooting below par.
Casey, bidding to become the first European to win the US Open since Tony Jacklin in 1970, battled hard to make amends for a number of wayward tee shots with four birdies against two bogeys.
"My putting was really good today," he said. "It was a case of not making mistakes. I went out with low expectations. The ball striking hasn't been great, and nor was it today, but I kept the ball below the hole for the most part and saved myself a couple of times. I'm ecstatic with 69."
I hit the ball well enough to shoot a good score but these greens are just awful
Micheel, the 2003 US PGA champion, was first home with a 69 after mixing five birdies with three bogeys, while the 29-year-old De Jonge, playing in his first US Open, was helped by holing out with a wedge for an eagle at the par-five 14th.
England's Poulter, who was one of the early starters to benefit from a lighter breeze and smoother greens on the fast-running course, shared a tie for fourth with Spanish debutant Rafael Cabrera-Bello, South Korea's KJ Choi, Canada's 2003 Masters champion Mike Weir, Germany's Alex Cejka and Japanese 18-year-old Ryo Ishikawa.
Donald, the world number six from England, recovered from a double bogey on the second with 11 straight pars from the eighth to end with a 71, while Northern Ireland's McDowell had an adventurous round of five birdies and five bogeys.
World number one Tiger Woods, who won his third major and the first of his three US Open titles by a record 15 shots when it was last held at Pebble Beach in 2000, began with eight straight pars and found the first 11 greens in regulation as he demonstrated a more controlled long game than in recent times.
But the 34-year-old, who has won 11 more majors since that famous victory 10 years ago, struggled on the greens and made bogeys on the ninth, 16th and 18th.
"I hit the ball well enough to shoot a good score but these greens are just awful, we were talking about it all day," said the American, who spent five months out of the game following a private-life scandal at the end of last year and has been troubled by a recent neck injury.
"You just can't leave yourself a long second putt. Hopefully it will be better tomorrow. You've got to be patient. If I didn't three-putt two times and lay up in a bunker my score would have been nearer where it should have been. But it's very tricky and difficult."
Westwood fought back from a terrible start at Pebble Beach
World number three Westwood suffered a nightmare start as he chases a maiden major title, dropping shots at the first, third and taking a double bogey on the fifth.
But the Englishman, who has finished in the top three in the last three majors, dug deep to fight back from five over after 12 to finish with a 74 that keeps him in touch.
The third member of the group, two-time US Open champion Ernie Els, ended two over after spoiling a steady round with a double bogey on the short 17th. The big-name trio will tee off at 0806 local time (1606 BST) on Friday.
Mickelson, the world number two, could usurp Woods at the top of the rankings this week, but the Californian struggled with his putter and ended four over after a round devoid of birdies.
"I just putted horrific," he said.
American Dustin Johnson, the winner of the last two PGA Tour events at Pebble Beach, albeit in softer conditions in February, also ended level par courtesy of birdies at 15 and 17 to cancel out a double bogey on the 14th.
Englishman Ross McGowan was among those on one over, while Ireland's three-time major champion Padraig Harrington ended two over, three weeks after minor knee surgery.
"It did look as if things were going the wrong way when it felt like the scoring should be better," he said.
"It evens out at the end of the day but certainly when I was four over par I didn't feel so good."
England's Ross Fisher, who finished fifth last year, also carded 74, while Northern Ireland's Rory McIlroy and Englishman Oliver Wilson ended on four over and Simon Khan, winner of the PGA Championship at Wentworth, was five over alongside Simon Dyson.