Billy Horschel took the limelight from world No 1 Rory McIlroy to win the biggest title of his career at the Tour Championship on Sunday, along with FedExCup honours and an eye-popping $10 million bonus.
Tied for the lead overnight with Northern Irishman McIlroy in the PGA Tour's season-ending playoff event, American Horschel held his nerve to triumph by three shots, clinching his third career victory on the U.S. circuit and second in two weeks.
Helped by a clutch par-saving putt from 30 feet on the 16th hole, the in-form Horschel signed off with a two-under-par 68 on a damp day at East Lake Golf Club for an 11-under total of 269.
"I'm on cloud nine, it's unbelievable," Horschel said after being presented with the Tour Championship and FedExCup trophies by PGA Tour commissioner Tim Finchem.
"It's just unbelievable, everything that's happened the last two weeks, and especially having a kid on the way. I'm not sure life can be better than this."
Horschel's wife, Brittany, is scheduled to give birth to their first child in two weeks' time.
McIlroy, seeking his fourth PGA Tour win of the year, fell out of contention with a double at the sixth and three consecutive bogeys from the ninth before closing with a 71, tying for second with American Jim Furyk (69).
"It was a week too far," McIlroy told NBC Sports after competing in his eighth tournament in a hectic 10-week run. "I was making mistakes that I don't normally make. But Billy deserved it. He played the best golf."
Horschel, one of five players who came into the tournament knowing that victory would automatically secure him the prized playoff crown, mixed three birdies with a lone bogey on Sunday to keep his closest challengers at bay.
The 27-year-old American ended his season with a spectacular flourish, having tied for second at the Deutsche Bank Championship earlier this month before winning last week's BMW Championship outside Denver.
Furyk made a sizzling start to the final round on a cool and overcast afternoon at East Lake, birdies on the second and third holes lifting him briefly into a three-way tie at the top with McIlroy and Horschel.
However McIlroy and Horschel made matching birdies at the par-four fourth to move one stroke clear, McIlroy sinking an 18-foot putt after missing the fairway off the tee and Horschel holing out from 11 feet.
Horschel edged one ahead by draining an 18-footer to birdie the par-four fifth, and was then handed a two-stroke lead when McIlroy double-bogeyed the tricky par-three sixth after dumping his tee shot into water.
Furyk trimmed Horschel's advantage by one with a birdie at the par-five ninth before faltering with a bogey at the 10th and McIlroy again stumbled with a bogey at the ninth after hitting a wild tee shot that sailed way right.
Horschel, who had reached the turn with a two-stroke cushion at 11 under, made his first mistake of the day with a bogey at the 10th where he ended up in the right rough both off the tee and with his second shot.
McIlroy also bogeyed the hole after three-putting, missing a three-footer for par, to slide four strokes off the pace.
Furyk joined Horschel in a tie for the lead at 10 under after very nearly holing out with a delicate chip from greenside rough for eagle at the par-five 15th, settling instead for a tap-in birdie.
But Horschel responded with a birdie of his own at the 15th, getting up and down from a greenside bunker to edge one stroke clear.
Just when it seemed that Horschel would bogey the par-four 16th, where his tee shot sailed right into trees from where he could only punch his second out on to the fairway, he sank an uphill 30-footer to save par before pumping his fist in relief.
Furyk gave Horschel welcome breathing space and a two-shot advantage when he bogeyed the par-four 17th after ending up short of the green in two.
"This one, Billy was out ahead," said Furyk, who also bogeyed the final hole and has not won on the PGA Tour since his victory at the 2010 Tour Championship.
"I was trying to chase him down all day. I just couldn't make enough birdies."
Horschel, playing in the final pairing right behind Furyk, narrowly missed a birdie attempt from 15 feet at the 17th before comfortably parring the last to seal a three-stroke triumph.