Wagner has yet to post a top 10 finish this year. At the Greenbrier, he broke a string of seven consecutive early exits.
In his two previous tournaments, he had three birdies combined. He had seven of them on Saturday.
"I felt really comfortable all day," Wagner said. "I hit a lot of good golf shots. I've got a really clear picture of what I'm trying to do on every swing.
"Sometimes when you're playing bad, you forget who you are and you get down on yourself. The last couple of weeks, I've just trying to be positive and remember that I've won three times out here. I'm a little more comfortable with myself right now."
Wagner played golf at Virginia Tech less than two hours from The Greenbrier resort, and hoots from Hokies fans could be heard around the golf course.
"It's great seeing a bunch of maroon-and-orange in the crowd," Wagner said.
He hopes they can see him wrap up his first win since the 2012 Sony Open.
Former BYU golfer Daniel Summerhays, who was one stroke back and tied for second place after the second round, shot a 73 Saturday and fell into a tie for 27th place at 5-under 205.
Sweden's Jonas Blixt was four strokes behind Wagner at 10 under after shooting 67. Australians Matt Jones (66) and Steven Bowditch (69) and Texas teenager Jordan Spieth (67) were at 9 under.
Second-round leader Matt Every bogeyed the first two holes and quickly fell off the leaderboard. He shot 74 and fell into a tie for 27th at 5 under.
In Saint-Quentin-En-Yvelines, France, Graeme McDowell of Northern Ireland and Richard Sterne of South Africa share a one-stroke lead after three rounds of the French Open. McDowell shot a 1-under 70 while Sterne had a 71 on the tough Albatross course of Le Golf National, leaving both at 5-under 208. Golf
Johnson Wagner -14
Jimmy Walker -12
Jonas Blixt -10
Daniel Summerhays -5