Phil Mickelson recorded a second-round 67 to open up a two-shot advantage at the Wells Fargo Championship.
The four-time major winner dropped just one shot to lead from American duo Nick Watney and George McNeil, while Scott Gardiner moved 21 places up the leaderboard to join them on seven-under-par.
World number two Rory McIlroy remained in contention with a 71 to sit three adrift, while Lee Westwood hit a 68 to join him on six-under-par.
England's David Lynn reached the halfway stage on five-under, while Sergio Garcia recorded a 68 to move to four-under.
Masters runners-up Angel Cabrera also made the cut, finishing on two-under-par to end the day in tied-26rd.
