Scott McCarron was second. He holed a 45-yard sand shot on 18 for a 64. Briny Baird (62), Garrett Willis (69) and Kevin Streelman (67) were six strokes back.
Leading after 54 holes in Greensboro usually leads to a victory. From 1998-2006, every champion of this tournament had held or shared the third-round lead, a string broken last year when eventual PGA TOUR rookie of the year Brandt Snedeker erased Jeff Overtons three-stroke advantage across town at Forest Oaks.
Then again, with low scores commonplace all weekend at the original Donald Ross-designed course, no lead is safe.
Where we are, and where Carl is, even if Carl stumbles and falls back, its still going to take a low number (Sunday) for somebody to win the tournament, Baird said. The golf course is set up for low numbers.
This time, Pettersson had three birdies and an eagle, opening with four pars before his 3 on the 529-yard, par-5 fifth. He landed his approach 4 feet from the pin and sank that putt to eagle the hole for the second time in three days.
But he also bogeyed the courses easiest hole ' the par-5 15th ' for the second day in a row. He sent his approach shot into the primary rough, recovered, then lipped out consecutive 4-foot putts to slip to 18 under.
He regained that stroke two holes later with a birdie on the par-4 17th after landing his fairway shot 4 feet from the flagstick. On the 18th, he left his 20-foot birdie putt 4 inches short and tapped in for par.
McCarron, who entered trailing Pettersson by four strokes, was bogey-free and had three consecutive birdies on Nos. 2-4 to move to 14 under. He finished strong with birdies on two of his final three holes ' the par-3 16th, and then his spectacular, round-closing shot from a downhill lie in the bunker.
I told my caddie if I made this, I would get in the bunker and do a snow angel, McCarron said. I chickened out.
Baird had the best round of the day, a 62 that included seven birdies on the back nine and birdies on his final four holes. He began the round 10 strokes off the lead but could only hope that Pettersson would somehow self-destruct on his hometown course.
I shot 28 on the back nine. He does something like that, the tournament is out of reach, Baird said. If he can be friendly and make a bunch of pars, it would leave a lot of people back in it.