The 40 year-old is three shots ahead of 2009 and 2010 winner Dustin Johnson, co-leader after the first round, who carded a 72 at Spyglass Hill.

Winless in his 167 Tour events, 18 year veteran Wi has suffered enough disappointment to know his next two days hinge on attitude.

"They are going to be a lot about demons and doubts," he said. "When things don't go well, I always got down on myself. I feel like I'm getting over that hump."

Tied for first in fairways hit and third in total putts, Wi should be confident and he might also have luck on his side.

He sank a 188-yard pitch on the par 4 14th for an eagle on a day full of exciting scoring.

Spencer Levin, who threw away victory at last week's Phoenix Open, carded four birdies, three bogeys, a double-bogey and two eagles to match Wi's 69 on Pebble Beach.

Padraig Harrington shot a brilliant 66 on the same course and sits in a five-way tie for third on eight under with Danny Lee, who shared Thursday's lead with Wi and Johnson.

Two shots back, tied for 17th, sits Tiger Woods, in his first Tour event of 2012.

Playing Monterey Peninsula, Woods was two under for the day despite never getting going with his putter and is striking the ball well enough to be a serious contender come Sunday.