South Korea's Si Woo Kim produced a nerveless display to become the youngest ever winner of the Players Championship as Ian Poulter had to settle for a share of second place.

Kim carded a final round of 69 at Sawgrass to finish 10 under par, three shots ahead of Poulter and former Open champion Louis Oosthuizen.

After his victory in the Wyndham Championship last year, Kim is the fourth player in the last 25 years to win twice on the PGA Tour before the age of 22, following in the footsteps of Tiger Woods, Sergio Garcia and Jordan Spieth.

And the 21-year-old is also comfortably the youngest winner of the so-called "fifth major" - surpassing the record set by former world number one Adam Scott, who was 23 when he won in 2004.

Kim began the day two shots off the lead shared by Americans JB Holmes and Kyle Stanley - but birdies on the first, seventh and ninth gave him a two-shot lead at the turn.

Poulter closed the gap with a birdie on the 11th but the 41-year-old Ryder Cup star three-putted the 12th to end his bogey-free run at 39 holes and did well to salvage a bogey at the last after a wild approach into the trees resulted in a penalty drop.

A run of nine pars in succession on the back nine was enough for Kim to seal victory, while Spain's Rafa Cabrera Bello produced a far more spectacular finish to claim a tie for fourth with Stanley.

Cabrera Bello holed out from 181 yards for the first albatross in tournament history on the 16th, then followed that with another two on the 17th, before holing from 35 feet for par on the last after hooking his tee shot into the water.

Poulter had slipped from a career-high of fifth in the world to 197th and just three weeks ago had seemingly lost his PGA Tour card until fellow professional Brian Gay alerted officials to a discrepancy in the points structure used for players competing on major medical extensions.

After playing just 13 tournaments in 2016 due to a foot injury, Poulter had 10 events this season to earn 218 FedEx Cup points or 347,634 US dollars (£269,755) to remain fully exempt.

He came up short in both categories after missing the cut in his 10th event last month, but Gay - who was also playing on a medical exemption after back problems - came to the rescue by discovering a difference between the way points were allotted this season compared to a year ago.

"From being in a position a couple of weeks ago where I wasn't here to finish tied second, it's a good week," Poulter said after his best finish since November 2014.

"It has been tough, it's been a tough 18 months. Today I felt like a couple of putts slid by, but I played well under pressure, barring that horrible second shot on the last.

"I've had the kids up here all weekend and had some fun on the beach and it's kind of taken my mind off things. From a playing perspective to be in this situation where I can play a schedule and enjoy some golf, some of my best golf has come out this week.

"I've enjoyed it and hopefully this is just a stepping stone to pressing on for the rest of this year."

Oosthuizen held the outright lead after he birdied the second and Stanley and Holmes - who slumped to a closing 84 which included an eight on the 17th - both bogeyed the first.

But the South African ran up a double bogey on the fourth and dropped another shot on the ninth, before following an eagle on the 11th with further bogeys on the 13th and 14th.

Further down the leaderboard, world number one Dustin Johnson finished outside the top three for just the third time this season in a tie for 12th.

Johnson saved his best until last by following rounds of 71, 73 and 74 with a closing 68 in a season which has already produced three consecutive wins and two runner-up finishes.

The 32-year-old has missed just one cut in nine tournaments this season, although he was forced to withdraw from the Masters minutes before his opening round due to a back injury suffered in a fall at his rented house in Augusta.

After holing from 50 feet for an eagle on the par-five second, Johnson dropped shots at the fourth and seventh before a birdie on the ninth took him to the turn in 35.

A regulation birdie on the 11th was followed by a remarkable one on the 12th, where Johnson's tee shot was hooked so badly it easily cleared the water hazard to the left of the green - but from an awkward lie the US Open champion pitched to within a foot of the hole.

Rory McIlroy's week came to a disappointing conclusion with a double-bogey six on the 18th in a closing 75, the world number two finishing two over par overall in a tie for 35th.

McIlroy is set to undergo an MRI scan later on Monday to determine the extent of an injury which hampered his efforts at Sawgrass. The four-time major winner hopes it is not a recurrence of the back and rib problem which kept him out for seven weeks earlier this season.