Billy Horschel took the limelight from world number one Rory McIlroy to win the biggest title of his career at the Tour Championship, along with FedExCup honours and an eye-popping $10m 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 US 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.

"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."

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."

FedEx Cup rankings:

1. Billy Horschel (US) 4750
2. Chris Kirk (US) 3100
3. Rory McIlroy (Britain) 3050
4. Jim Furyk (US) 2450
5. Bubba Watson (US) 2285

Source: Reuters