Scott Piercy has retained his spot at the top of the Safeway Open leaderboard but the second round is still to be completed after rain delayed play on Friday.
After a first-round 62, the American is currently four-under-par through his opening 12 holes to remain ahead of compatriot Johnson Wagner.
England's Paul Casey is a shot further adrift in third place but like Piercy and Wagner, he is yet to reach the halfway stage of the first PGA Tour event of the season.
Bill Haas holds the clubhouse lead but he is as many as six shots behind Piercy, while Phil Mickelson is in the top 10 after heading into the weekend trailing the leader by eight shots.
Scotland's Martin Laird is in a share for 10th position but still has 10 holes to play, but Ireland's Seamus Power faces a fight to make the cut when he returns to the course on Saturday morning.
Darren Plant
