Daniel Chopra notched his second straight round of 3-under 68 to end at 6-under-par 207. He shares third place with Tom Pernice, Jr. (70) and Davis Love III (70).
Pettersson opened with a birdie on the first. He stumbled to a bogey on three, but bounced right back with a birdie at the fourth.
The Swede converted a birdie try at the seventh and came right back with a birdie on No. 8. Pettersson birdied the 10th to get to minus-9, then parred his final eight holes.
'I have to stay patient tomorrow and not think ahead,' said Pettersson of the aspect of going for his first win on Sunday. 'I have to try my best and hope I can do it.
'I'll just try to stay calm and relaxed. Sunday is a new day and anything can happen in this game. I'll just try to be positive and I hope to play well tomorrow.'
Lowery opened with a birdie on the first. He gave that stroke back with a bogey on the sixth. The two-time winner on the PGA Tour drained a 12-foot birdie try on the 10th.
The 45-year-old got up and down for birdie on the par-5 11th to move one ahead of Pettersson at 10 under. Lowery stumbled to a bogey on the 13th.
Lowery ran in an 18-foot birdie putt at 16 to regain the lead. However, he gave that stroke right back as he bogeyed the 17th after his tee shot missed the green well right. Lowery parred the last to remained tied for the lead.
'I'm pretty proud of the way I hung in there today. It was a tough day,' Lowery said. 'I missed some greens and fairways and I kind of had to scramble a little bit. I made some good saves, including a real good save there on nine. I just kind of hung in there and I am pretty proud of the way I played.'
Chad Campbell posted a 2-under 69 in the third round. He stands in a tie for seventh at 4-under-par 209 with Bo Van Pelt and Tim Herron. Stuart Appleby, Dan Forsman and Robert Gamez are one stroke further back at minus-3.