SEA ISLAND, Georgia, Oct 21, 2012 (AFP) - Gainey nabbed eight birdies and holed out from a greenside bunker for eagle on the par-five 15th en route to a 10-under 60 that gave him a 16-under total of 264 and a one-shot victory over David Toms.
A birdie at the last would have made Gainey the sixth player in PGA Tour history to record a 59. He hit his approach inside 20 feet but his birdie attempt came up short.
Nevertheless Gainey trailed by seven shots entering the final round and his comeback matched the second-biggest for a victory on the tour this season.
Gainey's round included seven successive threes from the 11th -- four of them birdies and one of them his eagle.
He had to wait more than two hours to see if his lead would stand up.
"Got a long way to go," Gainey said as he walked off the 18th green, with the overnight leaders yet to make the turn.
When it was all over, Gainey was a little emotional.
"It's been a hard year for me and finally, we got it right," said the 37-year-old with an unconventional swing and the nickname "Two Gloves" for his habit of wearing gloves on both hands.
"I get bashed all the time about my swing," Gainey acknowledged, but added: "The only thing that matters is right before impact on the downswing."
Toms and Jim Furyk both made late runs, Toms finishing with a 63 for 265.
Furyk, still trying to erase the taste of America's Ryder Cup defeat to a storming European team at Medinah last month, birdied the 15th and made a great par save at 17.
He could have forced a playoff with a birdie at the last but instead hit his approach right and ended up with a three-putt bogey for a 69 that left him third on 266.
Furyk made just two bogeys all week, but he still couldn't break through for a first win of a season that has included seven top-10 finishes, a near-miss at the US Open and a tough loss to Sergio Garcia at the Ryder Cup.
"I think what I'm most disappointed about is when it came down the stretch, hitting the ball pretty much as good as I can, I made really, really poor swings at 17 and 18 with a seven-iron and eight-iron," Furyk said.
"So to play those two holes and not get one good look at it for birdie was disappointing."
Toms also needed a birdie at 18 to match Gainey but drove into a bunker.
"I was thinking about what kind of putt I was going to have before I ever hit the fairway," Toms said. "You get ahead of yourself and that's what happens."
Davis Love, who captained the losing US Ryder Cup team, had found a measure of solace in a strong performance this week in the tournament he hosts, but his dwindling hopes ended for good when he drove into the water on 16 en route to a double-bogey.
His one-over 71 left him tied for fourth on 268 with Zimbabwe's Brendon de Jonge (65) and D.J. Trahan (69).
Leading final-round scores on Sunday from the US PGA Tour $4 million McGladrey Classic (USA unless noted, par-70):
264 - Tommy Gainey 69-67-68-60
265 - David Toms 65-67-70-63
266 - Jim Furyk 66-65-66-69
268 - Brendon de Jonge (ZIM) 66-69-68-65, D.J. Trahan 66-67-66-69, Davis Love 65-66-66-71
269 - Greg Owen (ENG) 64-69-71-65, Chad Campbell 66-67-69-67, Charles Howell 66-68-67-68
270 - Charlie Beljan 66-71-68-65, David Mathis 69-69-65-67, Mark Wilson 68-69-66-67, Michael Thompson 65-68-69-68, Arjun Atwal (IND) 67-63-69-71
271 - Blake Adams 68-68-69-66, Scott Stallings 68-70-67-66, Daniel Chopra (SWE) 68-69-66-68, Harris English 71-66-66-68, Kyle Reifers 67-68-67-69
272 - Scott Brown 67-70-70-65, Sean O'Hair 73-66-67-66, Camilo Villegas (COL) 65-71-68-68, Brendan Steele 67-71-66-68, Bill Lunde 68-68-68-68, Ken Duke 67-68-68-69, Bud Cauley 62-70-68-72