(Reuters) - Northern Irishman Rory McIlroy capped a stunning comeback with a birdie at the fourth playoff hole to win the season-ending Tour Championship on Sunday, along with FedExCup honors and the mind-boggling $10 million bonus.

McIlroy rolled in a 15-foot putt at East Lake's par-four 16th to beat American Ryan Moore, sending the large gallery into a frenzy that might more likely be expected at next week's Ryder Cup.

"It was incredible," former world number McIlroy said at the victory presentation. "Sorry for the hoarse voice. I sort of lost my voice screaming at the end.

"I feel my game is coming together at the right time. Two wins in the last three feels pretty nice."

McIlroy, 27, vaulted into the playoff with a barnstorming finish to his final round, holing out from 140 yards to eagle the same hole where he would clinch the win 90 minutes later.

He closed his final-round 64 with a tap-in birdie at the par-five 18th and only joined the playoff with American Kevin Chappell (66) and Moore (64) when the latter's eight-footer to win in regulation lipped out.

McIlroy then squandered a golden chance to win it at the first extra hole when he missed a six-footer. Chappell was eliminated on the first extra hole.

McIlroy looked shell-shocked but regrouped to sink a seven-footer and stave off defeat at the third extra hole, before clinching it at the next.

"It was such a nice one, uphill, just outside the right edge," McIlroy he said of his winning putt.

"I knew if I hit a good putt it had a great chance of going in. To see that ball drop, everything has come together for me. To be able to come here and pull it off is really special.

"I've won the money list a few times in Europe but never been able to quite do it here, the FedExCup in the U.S. When you put your mind to it, great things happen."

McIlroy's gain was Dustin Johnson's loss as the U.S. Open champion would have won the FedExCup had either Moore or Chappell won the playoff.

Johnson started the final round tied for the lead with Chappell, but struggled to a 73 in ideal conditions to plunge to into a tie for sixth at five-under.

So instead it was McIlroy, the only member of the European Ryder Cup team in the field at East Lake, who clinched the season-long points race and $10 million bonus along with $1.53 million for the tournament victory.

(Reporting by Andrew Both in Cary, North Carolina; Editing by Frank Pingue)