Rivals Tiger Woods and Phil Mickelson shake hands after their starkly contrasting rounds Thursday in the US Open. Woods shot a 1-under 69, Mickelson a 6-over 76.

Bubba Watson tees off on the first hole during the first round of the 112th U.S. Watson struggled throughout the day, finishing with an 8-over 78.

David Toms lines up his putt on the 14th hole during the first round of the 112th U.S. Open Thursday. Toms managed a 69 to grab a share of second place heading into Friday's second round.

Tiger Woods is dwarfed by a greenside tree as he putts on Olympic's first hole Thursday. Woods would par the hole.

Bubba Watson hits a bunker shot on the third hole Thursday during the first round of the 112th US Open. Watson bogeyed the hole on his way to a 78.

Luke Donald, the top-ranked player in the world coming into the US Open, chips on the 7th hole Thursday. Donald struggled mightily at Olympic, shooting a 9-over 79.

Kevin Na lines up his putt on the third hole during the first round of the 112th U.S. Open. Na started quickly, getting to 2-under before finishing with a 4-over 74.

Tiger Woods, Phil Mickelson and Bubba Watson wait on the 13th tee Thursday during the first round of the 112th US Open at The Olympic Club. Mickelson and Watson struggled with their opening rounds; Woods played solidly.

Tiger Woods consults his notes during the first round of the 112th US Open at The Olympic Club. Woods is trying to win his 15th major championship.

Bubba Watson plays a bunker shot on the 15th hole during the first round of the US Open. The 2012 Masters champion encountered trouble early Thursday, with bogeys on four of his first nine holes.

Amateur Andy Zhang of China, the youngest golfer to play in a US Open at 14, hits a bunker shot on the second hole during the first round.

Phil Mickelson (left) and Tiger Woods walk to the green on the eighth hole Thursday.

Spectators go to great lengths to try to get a good look at their favorite golfers at the 112th US Open at The Olympic Club in San Francisco.

Branden Grace of South Africa pauses after hitting a shot on the 14th hole during the first round of the 112th U.S. Open Thursday at The Olympic Club in San Francisco.

Tiger Woods and Phil Mickelson walk off the 12th tee during the first round of the 112th US Open. Mickelson said before the tournament that he was excited about playing with Woods, because it usually brings out the best in him.

Phil Mickelson plays a shot from the rough during the first round of the US Open. Mickelson's opening-round 76, 6 over par, left him with much work to do on Friday.

Tiger Woods watches his tee shot on the first hole during the first round of the US Open at The Olympic Club. Woods had three birdies and two bogeys on his way to a 1-under-par 69.

Amateur Andy Zhang of China, 14, discusses a shot with his caddie, Christopher Gold, during the first round of the US Open.

Scott Langley watches his tee shot on the first hole during the opening round of the US Open in San Francisco.

Bubba Watson hits his approach shot on the 10th hole at The Olympic Club. It was not the start to the US Open that Watson had hoped for. He had seven bogeys and one double-bogey on his way to an 8-over 78.