Dustin Johnson birdied two of his final three holes on Sunday to shoot a four-under 66 and come from behind to win the St. Jude Classic.

Johnson finished at nine-under 271 and won by a stroke at the TPC Southwind.

The victory was Johnson's sixth on the PGA Tour and first since The Barclays last year. Johnson missed nearly three months earlier this season because of a back injury, and just came back last week.

"It feels really good., especially having so much time off, coming back," said Johnson. "You know, last week helped a lot competing and getting back in the groove of things. And then, you know, I came out this week and I really -- I just played well all week."

Now, he will head to The Olympic Club next week as a favorite for the U.S. Open. Two years ago, he held the 54-hole lead at Pebble Beach, another San Francisco area U.S. Open venue.

Johnson wasn't concerned with that on Sunday.

"I wasn't worried about the Open today," acknowledged Johnson. "Next is a whole different week. It has nothing to do with this week. I'm going to go out and get a game plan together to play that golf course and stick with it. Hopefully just give myself a chance to win on Sunday."

John Merrick, one of three third-round co-leaders, carded a two-under 68 and finished second at minus-eight.

It was an incredibly tight finish on Sunday as several players were doomed by water at the closing hole.

After birdies at 16 and 17, Johnson had a one-shot lead, but four golfers were within one.

Rory McIlroy, who will defend his title at The Olympic Club next week, trailed by one, but found water off the tee at 18 and made double-bogey.

"It was a bad swing at the wrong time," said McIlroy. "Overall, it's been a decent week. Looking forward to getting to San Francisco and I can take a lot from this week into next week."

Chad Campbell also got wet at the last, bogeyed the hole and finished two back.

Same thing happened to Nick O'Hern, the second of the trio in first after round three.

After all of the penalty drops, Campbell (68), O'Hern (69), Ryan Palmer (66) and U.S. Ryder Cup captain, and the final third-round leader, Davis Love III (69) tied for third at seven-under 273.

McIlroy built a two-shot lead with four birdies through his first 11 holes, but bogeys at 12 and 14 dropped him into a tie for first.

When Johnson made his birdies, and McIlroy his bogeys, McIlroy finished with a one-under 69 and shared seventh with Ken Duke (65), Seung-Yul Noh (66) and Robert Allenby (69). The group finished at minus-six.

Johnson began the final round just one off the pace, but with the leaderboard in constant flux on Sunday, he found himself tied for first on more than one occasion.

He started with a four-foot birdie on the first, then collected his second birdie of the round from 17 feet out at the sixth. Johnson made it two in a row thanks to a three-footer at the seventh and found himself tied for the lead at eight-under par.

Johnson fell off the pace when he couldn't get up and down from a back bunker at nine.

McIlroy pulled away a bit with a two-shot lead, but bogeyed 12, then three- putted the 14th for another bogey. That brought him down to seven-under, and thanks to several consecutive pars, Johnson was tied for the lead again.

Johnson missed the green right with his second at the par-five 16th. His chip ran 11 feet by the hole, but Johnson poured in the birdie effort to match Campbell in the lead.

McIlroy made a 20-foot birdie putt at 17 to make it a three-way tie for the lead.

Johnson, in the group behind Campbell and McIlroy, hit his second just inside nine feet at 17. He drained the birdie putt and moved one ahead.

McIlroy's tee ball at the last went left into the water and his hopes were dashed. Campbell hit it in a similar spot and his chances were all but gone, unless Johnson made a similar mistake.

He did not.

Johnson's drive landed in the short grass and his second safely came to rest 30 feet short and left of the flagstick. He lagged his birdie putt close, tapped in for par, then had to wait to see what O'Hern and Merrick did.

O'Hern's drive never threatened land and his opportunity was squashed.

Merrick was one back and his shot tee stayed dry, but went well right. He couldn't get his second to the green, so he'd have to hole a chip to force a playoff. Merrick couldn't do it and Johnson picked up his sixth PGA Tour title.

"I had a lot of looks, lot of good looks, and made a few putts coming down the stretch," said Johnson. "I played well yesterday, and then obviously I played really well today. Shot my best score of the week today on Sunday. If you do that, usually you're going to play well. You're going to finish up at the top of the leaderboard."

NOTES: Johnson pocketed $1,008,000 for the victory...Johnson, 27, has won in five consecutive seasons and has the most wins by a PGA Tour Player in his 20s with six...Tee times were moved up in anticipation of bad weather in the afternoon...McIlroy will defend his U.S. Open title next week at Olympic Club.