Tiger Woods remains a firm favourite for the US Open in San Francisco - and as he enters the weekend joint leader at one-under-par, defending champion Rory McIlroy and world number one Luke Donald are nowhere to be seen.

Woods added a 70 to his opening 69 and, with surprise first-round leader Michael Thompson going from three clear to two behind with a 75, that was good enough to put him at the head of things at halfway.

Four years on from the last of his 14 majors, but back to winning ways three times in the last seven months, Woods has two Ryder Cup team-mates for company.

Jim Furyk, now 42 and nine years on from his victory in the event, shot 69 and then 45-year-old David Toms, whose major title came at the 2001 USPGA Championship, matched Woods' round.

By then McIlroy and Donald knew their fate. The 23-year-old - an eight-shot winner on a record 16 under last June - crashed out on 10 over after a 73, while the only player ahead of him in the world rankings was one worse following a 72.

For both the damage had been done on the opening day.

There is still a chance of the trophy going back to Northern Ireland for the third successive year.

Graeme McDowell, champion down the Californian coast at Pebble Beach in 2010, reached two under, but three bogeys in his last four holes left him two behind.

McDowell said: "It's just tough to have fun out there, I've got to be honest with you. It's just a brutal test of golf.

"I'm disappointed to bogey three of the last four, but that's what this golf course can do to you in a heartbeat - and if you had offered me one over par starting on the first tee yesterday I would have probably snapped your arm off for it. I'm very happy to be where I am. I made enough birdies to kind of offset some mistakes, which I think's key."