Rory McIlroy rallied from six strokes down starting the final round to overtake top-ranked Scottie Scheffler and win his record third FedEx Cup title on Sunday by capturing the PGA's Tour Championship.

The 33-year-old from Northern Ireland fired a four-under-par 66 to finish on 21-under 263 at East Lake in Atlanta.

Four-time major winner McIlroy took the $18 million top prize in the season-ending playoff showdown by one stroke over reigning Masters champion Scheffler, who fired a 73 on Sunday, and South Korean Im Sung-jae.

"It's great to end the season on a high note like this," McIlroy said. "To do something no one else has done... and playing the golf when you needed to to get the job done -- incredibly satisfying."

Scheffler, who began the week on 10-under thanks to the season points lead and a staggered scoring system, lost out because McIlroy fired the week's best 72-hole score, 17-under.

"Just little mental errors," Scheffler said. "I just wasn't swinging it well.

"I really fought hard. Rory just played a really good round of golf. He made some key putts there at the end and he definitely deserved to win."

Scheffler, a four-time winner this season, earned McIlroy's respect.

"I feel like Scottie deserves at least half of this," McIlroy said. "I feel sort of bad that I pipped him to the post."

McIlroy, who has been a major advocate for the PGA Tour in its ongoing battle with the Saudi-backed LIV Golf Series, said victory was even sweeter given the tumult engulfing the sport this season.

"It means an awful lot," McIlroy said. "This is an incredbly proud moment for me but it should also be an incredibly proud moment for the PGA Tour. They have had some hard times this year but we're getting through it."

Fourth-ranked McIlroy, who won the 2016 and 2019 Tour Championships, roared back from 11 strokes back late in the second round and six shots down after 54 holes.

"I just showed so much resilience to claw my way back," McIlroy said.

"I didn't really give myself much of a chance teeing off today. I thought six behind, it was really going to be tough to make up.

"But my good play and Scottie's not-so-great play and it was a ball game going into the back nine."

McIlroy sank a stunning birdie putt at the par-3 15th from just inside 32 feet, the ball breaking to the left and dropping into the hole, to match Scheffler for the lead on 21-under.

McIlroy blasted out of a bunker way beyond the 16th green but pitched inside eight feet and made the par putt while Scheffler missed a par putt from just inside nine to hand McIlroy the lead.

Both parred 17 as the tension grew.

At the par-4 18th, Scheffler found a greenside bunker while McIlroy bounced his second shot off the left grandstand and into deep rough.

Scheffler went over the green out of the sand then pitched back onto the green while McIlroy chipped onto the green and two-putted for par and the victory.

"If you're willing to go out and earn it, this is what can happen," McIlroy said.

Money wasn't a thought

Scheffler said the $11.5 million difference in first and second was never on his mind.

"The money definitely didn't creep into my mind. I wanted to win the season-long title," he said. "I've had a really great year and I wanted to finish it off with a win here and unfortunately I wasn't able to do that."

Scheffler birdied four of his last six holes Sunday morning to finish the lightning-halted third round and stretch his lead from one stroke to six.

The big lead dwindled quickly with bogeys by Scheffler on three of the first six holes while McIlroy answered an opening bogey with a birdie at the third and made three birdies in a row starting at the fifth.

"I just didn't get off to a good start early, but after that I grinded as hard as I could," said Scheffler. "My swing wasn't where it had been the first few days."