ATLANTA -- Rory McIlroy of Northern Ireland shot a final-round 4-under-par 66 to clinch the Tour Championship in a long day of golf Sunday, Aug. 25, at East Lake in Atlanta.

McIlroy becomes the FedEx Cup champion, with his final score listed at a net 18-under 267 in the weighted scoring system being used in the FedEx Cup final.

His margin was four strokes on Xander Schauffele, whose final-round 70 put him at 14 under in the tournament.

McIlroy, now a two-time FedEx Cup champion, began the week in fifth place and trailed third-round leader Brooks Koepka by a stroke after the third round concluded Sunday morning.

McIlroy looked primed to cruise to the finish until bogeys on Nos. 14 and 15, putting his lead at two shots.

Justin Thomas and Koepka shared third place at 13 under.

Koepka, who shot 72 in the final round, tumbled from the lead with a double bogey on the seventh hole. He had birdied the hole in the second and third rounds.

It amounted to a three-shot swing because of McIlroy's birdie at No. 7 on Sunday afternoon.

Still, Koepka appeared in good position until consecutive bogeys on Nos. 12, 13 and 14.

Thomas, who began the tournament atop the standings and had the best chance of winning, posted 68 for the final round. Two birdies across the final three holes weren't enough for him to claim the FedExCup title for the second time in three years.

England's Paul Casey slumped with a final-round 72 and ended up fifth at 9 under. His third-round 68 was his previous high round for the tournament.

After finishing the suspended third round Sunday morning with a 68, Koepka held first place at 15 under.

He carried a one-shot lead on Schauffele and McIlroy entering the afternoon's play. Schauffele shot 67 and McIlroy posted 68 in the third round.

In that round, Schauffele aced the 240-yard ninth hole for his first-ever hole-in-one. He pulled into a tie for the lead with a birdie on No. 17, but Koepka's birdie on the final hole of the round put him back on top.

Those near the top of the leaderboard had more than half of the third round to complete when golfers returned to the course Sunday, which was the first time in three days that play wasn't interrupted by a weather delay.

Saturday's round was shortened because of a late-afternoon lightning strike that resulted in six injured spectators when debris fell from a tree. The round had been under a weather-related suspension at that point.

Thomas was atop the leader board when Saturday's competition ended. But his third-round 71 put him tied for fourth with Casey (68) at 11 under.

The best score of the third round was turned in by Japan's Hideki Matsuyama, whose 66 allowed him to move to 6 under for the tournament and into a tie for sixth place prior to the final round. His 71 in the afternoon left him at 5 under and tied for ninth.