“I still can’t believe I’m the champion and I’m the youngest champion for this major tournament,” Kim said through a translator. “I’m looking forward to working hard from now on.”

Resolute and cool under pressure, Kim used a bogey-free final round to collect his biggest victory by finishing 72 holes on 10-under 278.

Kim, ranked 75th in the world, became only the second non-US player to win twice on the US PGA Tour before age 22, joining last month’s Masters winner, Spaniard Sergio Garcia.

Britain’s Ian Poulter and South African Louis Oosthuizen shared second on 281, Poulter after a closing 71 with “Oosty” firing a 73. American Kyle Stanley and Rafa Cabrera Bello of Spain shared fourth on 282.

Kim, the US PGA’s youngest player, won his first tour title last August at Greensboro, but hadn’t managed a top-20 US PGA finish since last October and was in only his second Players, having shared 23rd in 2016.

“Usually I’m very nervous but last year I won one and I got a two-year extension,” Kim said. “So I can hit aggressively and I wasn’t as nervous.”

Now Kim has a five-year spot on the tour and assured spots into many of golf’s top events.

Stanley and countryman J.B. Holmes, who closed with an 84, were 54-hole co-leaders, but Holmes had bogeys on three of the first five holes and Stanley on two of the first four to stumble back.

Oosthuizen sank a four-foot birdie putt at the par-5 second to reach nine-under but found water at the fourth and made double bogey to fall back.

That left Poulter and Kim atop the leaderboard at eight-under, Poulter after a tap-in birdie at the second and five-foot birdie putt at the sixth and Kim after a 17-foot birdie on the opening hole.

Kim sank a 24-foot birdie putt at the par-4 seventh to seize the lead and sank an 18-foot birdie putt at the par-5 ninth to reach 10-under for a two-stroke advantage.

Then Kim parred his way through the back nine, his last putts no longer than four feet on any hole as he calmly ignored winds and tension to prevail.

Poulter could never catch him, reaching nine-under with a five-foot birdie putt at the par-5 11th but making bogey at 12, missing a five-foot par putt, and taking another bogey at 18 after shanking his approach 40 yards right into a bush but then smacking his fourth inches from the cup.

“It was one of the worst shots you will ever see to a pretty good one,” Poulter said. “I was nervous out there all day, being in a situation I hadn’t been in for a while.

“I felt good coming down the last few holes. I’m pleased I played well. It has been a good week.”

It was the second Players runner-up finish for Poulter after 2009. It came after he had thought his playing rights were lost before a recalculation of points showed he had done enough with a medical exemption to keep his tour spot.

Stanley made his fourth birdie of the week at the par-3 17th island green, matching American Paul Azinger from 1987 as the only players to birdie the hole four times in one week.

Northern Ireland star Rory McIlroy, who fired a 75 to finish on 290, travels to Belfast for an MRI exam Monday to see about nagging back pain that could be related to a rib injury that sidelined him earlier this year.