Kelly Kraft shot a seven-under 63 in the second round of The Greenbrier to take a one-stroke lead over first-round leader Webb Simpson and Anirban Lahiri.
Kraft posted his career-best round on Friday at the Old White TPC in West Virginia. He was at 13-under 127.
Lahiri overcame poor play off the tee to shoot a career-low 61, matching Simpson's score from the opening round.
American Simpson made five birdies after a lousy start and shot three-under 67. Both were at 12 under.
Veteran Victorian Cameron Percy carded a second round two-under 68 to be at five under and tied for 33th.
He will be the only Australian in action on Saturday and Sunday with Matt Jones (66), Stuart Appleby (68), Robert Allenby (70), Steben Bowditch (75) and Geoff Ogilvy (73) all missinf the three-under cut mark.
Jason Kokrak shot 64 and was alone in fourth place at 11 under.
Whee Kim of South Korea and Harold Varner III were at 10 under. Kim shot 68 and Varner shot 64.
Simpson is the only one among the top six players on the leaderboard with a PGA Tour win.
Since its 2010 debut, the tournament has produced four first-time winners, including three rookies.