By Mark Lamport-Stokes

SAN DIEGO (Reuters) - Twice champion Tiger Woods prepared to launch his bid for a 14th major title as the 108th U.S. Open began in overcast but dry conditions at Torrey Pines on Thursday.

Woods, who has not walked 18 holes since having surgery eight weeks ago, was scheduled to tee off in a high-profile grouping on the first hole at 8:06 a.m. local (4:06 p.m. British time) watched by huge galleries.

The American world number one has been drawn with second-ranked Phil Mickelson and Adam Scott of Australia, the world number three, for the first two rounds.

Woods, who had arthroscopic surgery on his left knee two days after finishing second at the Masters in mid-April, is heavy favourite to win the second major championship of the year.

U.S. Open champion at Pebble Beach in 2000 and at Bethpage Black in 2002, he has clinched the PGA Tour's Buick Invitational at Torrey Pines for the last four years and six times overall.

Left-hander Mickelson, a three-times major champion who lives in nearby Rancho Santa Fe, probably knows the course better than anyone else in the field.

He first visited Torrey Pines as a child and has won the Buick Invitational there three times -- in 1993, 2000 and 2001.

Defending champion Angel Cabrera of Argentina, who won last year's title by a shot at Oakmont Country Club, was scheduled to start off the first at 2036 with British Open winner Padraig Harrington of Ireland and American Davis Love III.

Other notable threesomes include South African Ernie Els, Australia's Geoff Ogilvy and Britain's Justin Rose; Fijian Vijay Singh, Spaniard Sergio Garcia and American Stewart Cink and a trio of Masters champions in South African Trevor Immelman, American Zach Johnson and Canadian Mike Weir.

World number 17 Luke Donald tees off from the 10th at 2014 in an all-British grouping with Paul Casey and fashion-conscious Ian Poulter, who is one of the most flamboyant dressers in the game.

The first blow of the tournament was struck by American journeyman D.A. Points, who is making his first U.S. Open appearance.

Playing with compatriot Patrick Shehan and Canadian David Hearn, Points split the fairway with his drive on the par-four opening hole.

Dry weather has been forecast for the rest of the day with bright sunshine expected in the afternoon.

(Editing by John Mehaffey)