Billy Mayfair (64), Anders Hansen (68), Carl Pettersson (68) and Tim Petrovic (68) were at 15-under 201, with 2003 winner Shigeki Maruyama (67) and Lucas Glover (66) four strokes behind Overton.
The 24-year-old Overton entered sharing his first lead of any kind in two years on tour with rookie Steve Marino and veteran John Huston. He took advantage of late struggles by strong-starting Craig Kanada to position himself for his first PGA TOUR victory.
Overton overcame a bogey on his first hole with birdies on seven of his next 11 to take control. He bogeyed No. 13 After a birdie on the previous hole got him to 18 under, but he got the stroke back with a birdie on the 16th.
Still, he wound up with the lead to himself at least partly because of Kanada's misfortune. Kanada, who entered the third round one stroke behind the leaders, led for most of the third round before running into trouble on the par-4 No. 16 hole.
He sliced his drive out of bounds, then three-putted his way to a triple-bogey that began his free-fall. He nearly sent his drive on the par-3 17th into the bunker and again three-putted, joining four other players five strokes back.
It was a harsh contrast to Kanada's hot start, when he birdied five of his first seven holes and made three putts from at least 15 feet out.
Kanada wasn't the only player to struggle late. Nathan Green briefly threatened to challenge, reaching 16 under with a birdie on No. 12.
Then came trouble: bogeys on the par-4 Nos. 14 and 16 sandwiched a double-bogey on No. 15 that dropped him well off the pace at 12 under.
Huston (72) couldn't keep up with Overton, his younger playing partner, and finished 12 under. Marino (71) was one stroke better.
But the round of the day was Mayfair's 64. He made the cut by just two strokes but now is within striking distance of his sixth PGA TOUR victory and first since 1998.
His lone bogey was offset by seven birdies and a hole-in-one on the par-3 No. 8, holing out from 202 yards with a 4-iron. It was an encouraging round for Mayfair, who came to Greensboro ranked No. 75 on the FedExCup points list and seeking a boost before the postseason starts next week.
'That's why I'm here this week -- to try and move up in my standings,' Mayfair said.