American Billy Hurley III fired a second-round 63, the second-lowest score of the tournament so far, to rise from 31st to the top of the leader board at the Greenbrier Classic on Friday.
Hurley holds a one-stroke lead over Chris Stroud, who hit his second straight 66, and Kevin Chappell, who followed up his first-round 67 with a 65.
Hurley hit four birdies in his first seven holes, and another three between No. 14 and No. 17.
Nobody was hotter on the day than Troy Matteson, who jumped from 110th to 4th with a second-round 61, firing nine birdies, including five in a seven-hole stretch on the back nine.
The 34-year-old Matteson is ranked 176th in the world.
A three-way tie for fifth is comprised of Steve Stricker, Chris Kirk and Brice Garnett.
Masters champion Bubba Watson rose from 31st to a tie for eighth with a 67 to get to 5-under.