CONCORD, Massachusetts (Ticker) -- Bob Gilder is getting the hang of this playoff thing.

Gilder won a Senior PGA Tour event in a playoff for the second straight week, tapping in a birdie putt on the third extra hole Sunday to defeat John Mahaffey and claim the FleetBoston Classic.

"I learned a long time ago not to get too high and too low," said Gilder, who collected his fourth career Senior Tour victory. "I've always been the type of person who doesn't get too nervous."

Gilder became the first Senior Tour player since Lee Elder in 1985 to win back-to-back tournaments in playoffs.

Last week, Gilder won the SBC Senior Open by beating Hale Irwin -- the best player on the tour -- on the first playoff hole. On Sunday, it took him two holes longer to dispatch Mahaffey, who caught Gilder with a final-round 65, the best round of the day.

The duo each parred the par-5 18th and par-3 17th before returning to the 18th. Gilder's second shot landed scant feet from the green, while Mahaffey still needed more than 100 yards to the hole.

"I just didn't have a club to get there in two," Mahaffey said. "I'm too old now."

Mahaffey reached the green, but his ball settled below the pin, leaving a 30-foot birdie attempt. Gilder executed a perfect pitch-and-run that stopped 18 inches from the cup.

After Mahaffey just missed his long putt, Gilder tapped in to claim the $225,000 first prize. He moved into second place behind Irwin on the money list with $1.32 million and the Charles Schwab Cup standings with 1,115 points.

"This win was overwhelming," Gilder said. "I didn't expect this one."

Gilder held or shared the lead after each trip over Nashawtuc Country Club. However, he was a bit lucky Sunday, when a 2-under 70 left him with a 54-hole total of 13-under 203.

"I missed a lot of putts, but I made a couple I needed to make," he said.

Jim Thorpe missed a pair of putts on the final hole of regulation that cost him the tournament. With a chance to win outright, he rolled a downhill four-footer too fast past the cup, then missed the comeback four-footer for a bogey that dropped him to 70-214.

"It was just embarrassing," Thorpe said. "I've never three-putted one from that distance. I'd like to go back and do it again. It shocked me that the ball went that far by."

"I thought it was over at the 18th hole," Gilder said. "(It was) pretty disheartening for Jim to do what he did. I felt bad for him. I knew his next putt would be an easy one to miss."

Gilder had his own problems at 18. After taking sole possession of the lead with a birdie at the par-3 17th, he bogeyed the final hole of regulation.

"I'm surprised more people didn't make a run today because I didn't stretch it out," Gilder said. "I thought my shot at 17 was going to do it, but the gods had something different in mind."

Mahaffey's only problems came before the round, when he was overcome with back spasms that nearly forced him to withdraw. On the advice of Dave Eichelberger, he took some treatment in a trailer.

"Eichelberger convinced me to go in the trailer this morning," he said. "I was about to withdraw today. When Eichelberger come off the 18th green, he said, `You owe me some money.'"

Mahaffey overcame an early bogey with three straight birdies beginning at the fifth hole. He added five more on the back nine, including two that closed his round and ultimately forced the playoff.

"I'm not surprised Mahaffey shot the score he shot," Gilder said.

Gilder became the fifth multiple winner on the tour this year, joining Irwin, Tom Kite, Doug Tewell and Bruce Lietzke.

Eichelberger shot a 69 and finished tied with Thorpe at 214, one stroke better than Wayne Levi and Larry Nelson. Levi, a former PGA Tour Player of the Year, carded a 68. Nelson, the two-time defending champion, matched Mahaffey for the day's best round with a 65.

Irwin followed consecutive 71s with a 66 and finished tied for 12th at 208.