NORTON, Mass. (AP) -- Three holes into the Deutsche Bank Championship, Rory McIlroy had to make a 15-foot putt just to escape with triple bogey.
He already was 4-over-par and had every reason to believe this tournament was headed for an outcome that was becoming far too familiar for a player of his class. But there was one difference.
His head didn't drop. His shoulders didn't sag.
McIlroy went from a miserable start to a memorable finish, closing with a 6-under 65 on Monday to make up a six-shot deficit and win the Deutsche Bank Championship for his 20th career title around the world.
"It's just incredible, this game, how quickly things can change," McIlroy said after his two-shot victory over Paul Casey. "It's been a great lesson for me this week not to get down on myself, to stay patient. After three holes Friday, there was so much going through my head, and none of those things involved sitting beside a trophy."
Not just a trophy, but a belt, too.
Deutsche Bank gave him the blue belt with a large silver buckle when McIlroy won four years ago, and because this was the last year it is sponsoring the tournament, the company wanted him to keep it.
"World heavyweight title," McIlroy said of the belt.
Not quite, but certainly a step in that direction.
A new putter, a new putting coach, and suddenly he looks like the McIlroy of old. It was his first PGA Tour victory of the year and moved him to No. 4 in the FedEx Cup, all but assuring him a clear shot at the $10 million bonus when he gets to the Tour Championship at the end of the month.
In a strengthening wind from Hermine that penalized the slightest misses at the TPC Boston, McIlroy closed out the front nine with three straight birdies to take the lead for the first time, went ahead to stay with a 20-foot birdie on the 12th hole and left no doubt with a 3-wood into the wind and over the hazard on the par-5 18th hole that set up a birdie from the bunker.
Casey, who started the final round with a three-shot lead in his bid for his first PGA Tour victory since 2009, closed with a 73. He had a 60-foot eagle putt on the final hole that would have forced a playoff. It went 8 feet by and he missed the meaningless birdie putt.
"Wow, very impressive. Yeah, that's a might round of golf," Casey said of McIlroy's finish. "I struggled a little bit from the get-go and it's hard to regain rhythm and make your birdies if you started out that way, so I found it incredibly difficult. I battled well, did a lot of things brilliantly all week, but obviously frustrated."
The only consolation for Casey was that his runner-up finish moved him from No. 59 to No. 10 in the FedEx Cup, assuring a spot in the Tour Championship for the first time since 2010. PGA champion Jimmy Walker closed with a 70 to finish third.
The top 70 advance to the BMW Championship, which starts Thursday at Crooked Stick in Indiana. Among those who moved into the top 70 was David Hearn of Canada, who came into the week at No. 92. Hearn closed with a 70 and tied for eighth.
McIlroy, who finished at 15-under 269, moves back to No. 3 in the world.
The 27-year-old from Northern Ireland fell out of the "Big 3" conversation earlier this year when Dustin Johnson won the U.S. Open, Henrik Stenson won the British Open and McIlroy kept sliding, largely because of his putting. His only victory was the Irish Open in May, and when he missed the cut in the PGA Championship, he sought out popular British putting coach Phil Kenyon. McIlroy also switched putters last week at Bethpage Black, though he was at the bottom of the pack in putting.
Not this week.
He didn't need to make everything in the final round, with his driving and short game setting up three early birdies. But he made an 18-foot birdie on the par-3 eighth, and followed that with a 10-footer on the ninth to make the turn in 31.
As the wind picked up, no one could stay with him.
"I wasn't getting impatient. I wasn't searching," McIlroy said. "I know that I hadn't won on the PGA Tour in a while, but over the past 12 months, I've still had three wins worldwide. ... I knew my game was in good shape, I just needed to do something with the putting. I found something. I still need to keep going with it. It's definitely not the finished article, but it's a big step in the right direction."