Jason Day survived a few anxious moments to cement his position as world number one with a seventh victory in his last 17 events in the Players Championship on Sunday.

Day carded a closing 71 at Sawgrass to finish 15 under par and four shots ahead of American Kevin Chappell, with Justin Thomas, Matt Kuchar, Colt Knost and Ken Duke a shot further back.

The 28-year-old began the final round with a four-shot lead, but struggled to reproduce the form which saw him equal the course record on Thursday and set a tournament best halfway total of 129.

Day's lead was cut in half when he followed a bogey on the sixth with another on the ninth after amazingly fluffing three consecutive chips from the side of the green, but for the second day running he played the closing stretch in three under par to seal a hard-fought win.

"It's such a big accomplishment for me in my career to be able to finally win as number one in the world," Day told Sky Sports. "And to go wire to wire is very special.

"I'm glad I don't have to play the course again. It was tough. It was easy to lose a little bit of focus on the front side, especially with a four-shot lead, and I just kept telling myself 'Keep yourself in it and give yourself opportunities on the back side'.

"I played really solid golf on the back side and am very pleased to walk away the champion."

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The win saw Day join Tiger Woods, Phil Mickelson, Adam Scott and Martin Kaymer as the only players to have won the Players Championship, a major title and a WGC event in their career.

And the US PGA champion also matched Woods (twice), Tom Watson and Johnny Miller in recording multiple wire-to-wire wins in a season following his victory in the Arnold Palmer Invitational at Bay Hill in March.

Chappell claimed second place thanks to a brilliant back nine which saw him chip in for an eagle on the 11th and birdie the 16th and 17th, with Thomas having earlier set the clubhouse target on 10 under with a 65, the lowest round of the day.

"It feels great," said Thomas, who won his first PGA Tour title in Malaysia last year. "I feel like I really played well all week, I just didn't have that much to show for it.

"I've got off to good starts and let some good rounds go, especially on the back nine where I feel like there are a lot of birdie opportunities, so it was nice to finish well today."

A second consecutive 69 lifted Graeme McDowell into a tie for ninth, with fellow Northern Irishman Rory McIlroy carding a 70 to finish a shot behind in 12th, thereby missing out on a fourth straight top-10 in the event.

England's Justin Rose was two shots further back after a closing 66 containing two bogeys and eight birdies, the last four coming in a row from the 14th.

"They definitely backed up the greens today," Rose told Sky Sports. "I think there was only one cut and one roll instead of... I don't know what the heck they did yesterday.

"It was fun. We knew were going to get some decent scoring conditions playing early this morning so it was nice to finish strong with a 66."

Rose was one of the few players to take a positive approach to the tough conditions despite a 78 on Saturday, seeing them as good preparation for the upcoming US Open at Oakmont.

"Once I got my head around it I quite enjoyed the challenge and relished it because Oakmont is going to be somewhat similar," the world number 10 added. "Once my score started going sideways I started to use it as practice to get my eye in."