Jordan Spieth of the US watches his second shot on the ninth hole during the first round of the Wells Fargo Championship PGA golf tournament at the Quail Hollow Club in Charlotte, North Carolina May 2, 2013. [Photo/Agencies]

SILVIS, Illinois -- Nineteen-year-old Jordan Spieth outlasted David Hearn and Zach Johnson on the fifth hole of a playoff to win the John Deere Classic on Sunday, becoming the youngest winner on the PGA Tour in 82 years.

Spieth, who doesn't turn 20 for another two weeks, hit a two-foot par putt to earn a spot in the British Open field at Muirfield. He is also the first teenager to a PGA title win since Ralph Guldahl took the Santa Monica Open in 1931.

"I didn't think it would happen this early," said Spieth, who turned professional in December. "I had a plan. I guess the plan got exceeded."

Spieth started the day six shots behind third-round leader Daniel Summerhays. But he forced his way into the playoff by holing out of the bunker from 44 feet on the final hole of regulation.

Spieth got lucky when that shot took a pair of fortuitous bounces. But he also put himself in that position with a brilliant final round.

"The shot on 18 was the luckiest shot I ever hit in my life," Spieth said. "The fact that it bounced right and hit the pin and dropped down to the cup, it's just extremely fortunate."

Spieth, Hearn and Johnson then made par on the first four playoff holes, but Spieth made another par to stave off Johnson and Hearn on the fifth.

Johnson, the defending champion at Deere Run, seized control midway through the final round of regulation, but he simply couldn't get enough birdies to put the field away, and his uncharacteristic bogey on No. 18 set up a three-man playoff.

All three players had their chances to make a playoff-ending shot _ with Johnson narrowly missing from the back of the green on a chip shot that clipped the cup on the first playoff hole.

Johnson hit the ground in disbelief. It would turn out to be the closest he would get to victory.

"I had my chances on the back side in regulation. I mean, I hit some really good shots and just didn't make anything," Johnson said.

Hearn also had a shot at the win, which would have been his first on the PGA Tour, as well. But he missed a makeable putt on the fourth playoff hole.

"Congrats to Jordan. He's going to have an amazing career, obviously. He's an incredible talent to come on Tour at his age and have as much success as quickly as he has. So hat's off to him," Hearn said.

Spieth, Hearn and Johnson all went right on their final tee shot. Spieth scrambled out of the rough, though, finding the back of the green to save par and win his first PGA Tour event.

Tiger Woods, Phil Mickelson and Rory McIlroy were all 20 when they earned their first victories, but none of them could match Spieth, who is now the fourth-youngest winner in Tour history.

"Just got so lucky. That's what it is. But right now I'm extremely pleased, and a little worried about only having short sleeves going to Scotland," Spieth said.