Right when it started to go wrong, Justin Thomas delivered his biggest shots Sunday in the BMW Championship.

In a span of three holes around the turn at Medinah (Ill.), his six-shot lead shrunk to two. Thomas answered with two clutch wedge shots, two big putts and sailed to a 4-under 68 to finish at 25-under 263 and secure a three-shot victory over Patrick Cantlay, who gave him a battle to the end with a 65.

"Patrick played unbelievably, put a lot of heat on me," Thomas said. "In the end, it could have been good for me. It kept me focused, kept my head down. ... I was really nervous going into today. I remembered that it's really hard to win a golf tournament."

His first victory since the World Golf Championship at Firestone last year moved him to the top of the FedEx Cup standings going into the Tour Championship, where he will start the tournament on Wednesday at 10 under par with a two-shot lead under the new scoring format as the final 30 players chase a $15 million first prize.

Only seven players dating to 1928 had ever lost a six-shot lead on the PGA Tour. Thomas didn't want to be the next. That's why he shut off his phone on his way to the course. It seemed everyone but him had already declared him the winner.

"Guys giving me advice in the locker room how to finish off a tournament," Thomas said. "I was like, 'I've done this a couple times, guys, but thank you.' It's a lot of the outside noise that makes it harder sometimes."

Cantlay, who made four straight birdies around the turn, secured the No. 2 position and will start at 8 under. Brooks Koepka will be 7 under, a staggered start all the way down to even par for the final five players. That includes Lucas Glover, who went bogey-double bogey until finishing with a two-putt par from 40 feet to secure his first trip to the Tour Championship in 10 years.

It will not include Tiger Woods, the defending champion. Wood, a long shot going into the final round to crack the top 30, closed with a 72.

Hideki Matsuyama shot his second 63 of the tournament and finished alone in third, making him one of three players who moved into the top 30 to reach East Lake. The other was Jason Kokrak, but only after J.T. Poston made bogey on his final hole.

PGA Champions

Doug Barron became the 13th Monday qualifier to win a senior tour event, holing two 15-foot birdie putts after a rain delay to beat Fred Couples by two shots in the Dick's Sporting Goods Open in Endicott, N.Y.

Making his second senior start after turning 50 in July, Barron closed with a 6-under 66 at En Joie Golf Club to finish the wire-to-wire victory at 17-under 199. With Couples in the clubhouse after a 63, Barron returned from the rain delay to hole the first 15-footer on the par-4 15th and break a tie for the lead, then doubled the advantage on the par-3 17th.

After tying for fifth in the Senior British Open in his Champions debut, Barron got into the field Monday with a 66 at The Links at Hiawatha Landing.

"I've got a place to play right now," Barron said. "I've got to reset my goals a little bit. It's not the Emerald Coast Tour anymore."