ATLANTA — Xander Schauffele ended his rookie season by winning the Tour Championship. Justin Thomas ended the best season with the FedEx Cup.
Schauffele, a 23-year-old from San Diego who was worried about keeping his PGA Tour card about three months ago, swirled in a 3-foot birdie putt on the final hole Sunday for a 2-under-par 68 and a one-shot victory over Thomas.
He became the first PGA Tour rookie to win the Tour Championship since it began in 1987.
Thomas never had more reason to celebrate finishing second. He capped off a season of five victories, including his first major at the PGA Championship, by claiming the FedEx Cup and its $10 million bonus.
It was the first time in eight years that two players celebrated at East Lake. Tiger Woods won the FedEx Cup and Phil Mickelson won the Tour Championship in 2009.
The surprise guest to the party was Schauffele.
‘‘It’s been a wild ride,’’ he said.
It began with a tie for fifth in his US Open debut, and he followed that a month later by winning the Greenbrier Classic. He wouldn’t even have been at the Tour Championship until he played his final six holes in 6 under last week at Conway Farms to get into the top 30 in the FedEx Cup.
And then he played like he belonged on such a big stage, especially on the back nine.
Starting on the par-3 11th hole, he one-putted four straight greens from outside 6 feet — one of them for birdie, the rest for pars, all of them clutch. Thomas caught up with birdies on the 16th and 17th, but the PGA champion missed the fairway on the 567-yard closing hole and couldn’t reach the green in two. His 25-foot birdie putt snapped off to the left just in front of the cup.
Schauffele saved par from right of the 17th green for the fourth time on the back nine, and then smashed a 347-yard tee shot on the 18th that left him an approach just short of the green. He putted that up to 3 feet and then nearly missed.
The ball hit the left edge and swirled 270 degrees before dropping in the front.
But it was enough to finish at 12-under 268, a victory worth $3.75 million, $2 million of that for finishing third in the FedEx Cup. He also moved to No. 32 in the world.
Thomas was among the first to congratulate him outside the scoring room.
‘‘It was a grueling day for sure,’’ Thomas said.
Schauffele is another member of the high school class of 2011, and by far the most unheralded against the likes of Thomas, Jordan Spieth, Daniel Berger, and others. Asked earlier in the week what he knew about Schauffele, Thomas replied, ‘‘Not much, except that he’s very good or he wouldn’t be here.’’
Thomas won more than the FedEx Cup. He also wrapped up the PGA of America’s points-based award for player of the year. He’s a lock to get the players’ vote as PGA Tour player of the year, and he won the Arnold Palmer Award for claiming the money title with more than $10 million.
Thomas wrapped up the FedEx Cup when Spieth, the No. 1 seed, couldn’t sustain momentum after holing out from the 10th fairway for eagle and nearly holing out again from the 13th fairway. Spieth closed with a 67 and tied for seventh, earning a $3 million bonus for finishing second in the FedEx Cup.
He had few regrets, not after a season in which his three victories included the British Open for the third leg of the career Grand Slam.
‘‘J.T. obviously is very well deserving of winning the FedEx Cup,’’ Spieth said. ‘‘Not winning a playoff event, I almost cheated my way into winning the FedEx Cup when he really deserved it.’’
Thomas had the FedEx Cup wrapped up with two holes to play thanks to mistakes behind him.
Paul Casey, who now has gone 144 starts on the PGA Tour since his last victory in the 2009 Houston Open, lost a two-shot lead in five holes but was still in the game until he put his tee shot into the water on the par-3 15th. He played alongside Kevin Kisner, who also went into the water and lost his chance of winning at East Lake.
Kisner had a 70 and tied for third with Russell Henley, who shot a 65. Casey closed with a 73 and finished fifth.