Scott had what he called an "indifferent" front nine where he bogeyed twice, letting Gay take a two-stroke lead at 8 under with two birdies over four holes. But Gay drove into the middle of the lake on the par-4 12th, setting up consecutive bogeys.
The Aussie didn't waste the opportunity.
He birdied Nos. 13, 15 and 16, taking the lead back to himself after hitting an iron within 4 feet on the 13th and holing a 13-footer on 15 to move to 8 under. He birdied the par-5 16th after lipping the edge of the cup from 10 feet for an eagle Scott still wished he hadn't missed that could have put him at 10 under.
Scott, who has not bogeyed once on the back nine this week, said he would have worried about Gay if he had kept making birdies.
"I was happy to get it together on the back nine after an indifferent front nine but turned it around and played some good golf and had a chance to really make a move with the eagle at 16. Would have been nice, but very happy with the finish anyway," Scott said.
Toms, who hasn't finished worse than 10th at the TPC Southwind since 2001, put himself in position to challenge Scott with five birdies and a bogey. He lipped out a 3-footer for birdie on No. 16.
The Shreveport, La., resident who usually has his share of LSU fans cheering him said difficult pin placement mixed with the grain of the Bermuda greens, which replaced the bentgrass after 2004, make putting very difficult. He three-putted No. 7 for bogey.
Toms also came here to tune up for the Open, and he said he is glad to have the chance to win.
"No matter how I play, I feel like I'm on the road to feeling very confident about my game and in good shape going into the U.S. Open, which you need to be because I know it's going to be a very difficult test up there," he said.
The par-4 ninth single-handedly knocked Buckle off the pace with a pair of double bogeys hours apart.
The first came with Buckle at 6 under Saturday morning finishing up his second round. Grouped with Gay and Scott in the third, Buckle drove in the right rough and hit his third onto the green only to watch it trickle back within a foot of the water and he couldn't get up and down.
He finished with a 75 and was at 1 over overall.
Divots: Jose Coceres withdrew after nine holes because of back problems. ... Ken Duke had the best front nine Saturday, shooting a 31. The native of Arkadelphia, Ark., bogeyed four of the first five holes on the back nine and finished with a 70 for a 2-over total. ... Nathan Green holed a putt from 54 feet for birdie on No. 13. It didn't help much. He shot a 73 and was tied for 72nd.