Pettersson, who can avoid U.S. Open qualifying with a victory, was among 24 players who had to return at 7 a.m. to complete the third round because of storm clouds that gathered, the third straight day the round did not finish because of bad weather.
Pettersson was at 11-under 205, and he was the only contender not to lose any shots when he returned.
Woody Austin was at 10 under and was some 30 feet away, just off the back of the 18th green. His chip ran 7 feet by the hole, and he missed the par putt to shoot 67 and finish at 9-under 207.
Zach Johnson, whose four straight birdies put him into contention at 10 under, found a bunker on the 17th and made bogey, then had his ball spin off the green on the 18th that led to another bogey. He wound up with a 70 and was three shots behind at 208.
Masters champion Phil Mickelson was in the middle of the 18th fairway at 8 under, but he pulled his approach into thick rough, hit a flop shot that rolled softly toward the hole, but he pushed his 6-foot par putt and had to settle for a 70 that left him at 7-under 209.
Also struggling was Adam Scott. He was at 8 under and in good shape in the 17th fairway, but missed the green well to the right in rough so deep that it took him two shots to reach the green, taking double bogey. Scott did well to limit the damage to that. On the 18th, he hit into a fairway bunker, then got it out and onto the green about 50 feet away and walked off with par. He shot 73 and was at 210, five shots behind but still in contention.
Everyone will have to catch Pettersson, who will try to win for the second time in seven months.
This one would be meaningful, because the Swede was No. 51 in the world ranking that came out Monday, and the top 50 were exempt to the U.S. Open. He is scheduled for a 36-hole qualifier Monday in nearby Columbus, but the final exemption available is for anyone winning multiple PGA Tour events since the last U.S. Open.
Pettersson needed a few good breaks to build his cushion.
He made bogey from the bunker on the 16th hole, then got it back with a 45-foot birdie putt on the 17th. He was headed for a messy conclusion on the 18th, however, when his approach went into the cabbage right of the green, buried so deep that he and his caddie had trouble finding it.
Pettersson asked a rules official for relief, claiming he was in casual water, hopeful the official would agree so that he could take a free drop and the ball wouldn't be so deep in the grass. The consultation lasted all of about 5 second -- the answer was no -- and Pettersson showed he really didn't need it.
He chopped at the ball and it barely hopped into the fringe, trickling 2 feet from the cup for his par.
Trevor Immelman of South Africa, coming off two runner-up finishes, shot 69 and was in the group at 5-under 211 that included Dallas winner Brett Wetterich, Bay Hill winner Rod Pampling and Sean O'Hair.