Bobby Clampett was second after a 65.
"I was just really trying to hang in there," Clampett said. "I wasn't playing particularly well early on in the round and missed a couple shots tee shot at 7 and a tee shot at 9 and managed to squeak out a couple bogeys on those holes. I just hung in there a made some good putts today."
Tom Pernice Jr., David Frost and Michael Allen were 11 under. Pernice had a 64, and Frost and Allen shot 66.
"Today was a good day to get me closer to the lead, so I'm within striking distance," Pernice said. "I'm going to have to play good again tomorrow though."
Jay Don Blake matched the tour record with three eagles en route to a 66 that left him at 10 under along with Kirk Triplett (66), Jeff Sluman (68) and Bart Bryant (68).
Mike Goodes was in the group at 9 under after matching Mediate's course record with a 63.
"I was walking down the last few holes saying if you can't have fun doing this, you can't have any fun, so I was enjoying it," said Goodes, who had eight birdies in his bogey-free round. "It was a great round and I got in position where I can have a really good tournament."
Fred Couples was 8 under after a 65.