TULSA, Oklahoma: South Korean-born An Byeong-hun defeated Ben Martin 7 and 5 in the 36-hole final Sunday to become the youngest champion in US Amateur history.

The 17-year-old high school student emerged from a field at Southern Hills Country Club that featured many of the top college players in the country.

An was 9-over par on the day, but that still put him well ahead of the struggling Martin.

“I can’t believe it. I just won,” said An, who was missing the first week of school at Florida’s Bradenton Preparatory Academy to play in the tournament. “I’ve said it before, but my goal was to make it to the first round and then somehow I made it this far. I think I got lucky.” An, the second straight champion born in South Korea, took a 3 up lead by winning three of the last four holes in the pairing’s first of two 18-hole rounds. He doubled that edge as Martin bogeyed five of the first seven holes in the afternoon round, then closed it out after a short-lived comeback attempt by Martin the second time through the back nine.

An, who turns 18 on Sept. 17, is about a month and a half younger than Danny Lee was when he broke Tiger Woods’ record last year to become the US Amateur’s youngest champion. Lee was 18 years, 1 month old at the time of his victory, while Woods was seven months older than that when he won his first of three straight titles.

Other past champions include Jack Nicklaus, Arnold Palmer and Phil Mickelson.

An left his life and his mother half a world away and moved to a country where he didn’t speak the language to learn the game he’d first tried out by chance one day while his father was hitting balls at the driving range.

He entered the 109th US Amateur in hopes of making it through the stroke-play qualifying portion and into match play.

“It was a good decision, I think. Thanks to my dad telling me to come over here to play golf. It was definitely worth it,” An said. “I guess I’ll have to try to win the bigger ones now.” An will take home the Havemeyer Trophy to put alongside the Olympic table tennis medals won by both of his parents at the 1988 Seoul Games.

His father, Jae, spent the week caddying for him and providing advice - sometimes to the point that An had to tell him to stop talking.

“He was saying the same thing all day, but it helped,” said An.

Martin led at the turn in the morning round and the match was all square after Martin knocked his tee shot at No. 14 off the flagstick, then had to recover for bogey when his ball rolled all the way off the green and into a bunker. It was a sign of things to come.

An won the next three holes, following Martin’s three-putt at No. 15 by sinking a 15-foot birdie putt at the 15th.

Martin then drove over the green on the par-4 17th, flubbed a chip and couldn’t recover.

He briefly sliced into the lead when An made bogey to start the afternoon, but then hit over the green again and had to take a drop before settling for bogey. That started a stretch in which An won four of six holes without ever making a birdie.

An moved to 6 up after 25 holes when Martin hit his tee shot into the trees left of the fairway and scrambled to hit his second shot through branches within 50 yards of the hole. He took off his hat and mishit his chip into a greenside bunker, on his way to yet another bogey.

Martin won back-to-back holes at the final turn to get to 4 down, but An slammed the door by winning the next three holes - starting with a birdie at the par-3 11th.

“He’s a good player, no matter how old he is,” said Martin, 22. “I was just out there trying to play my game and do what I needed to do, but I didn’t have it going and wasn’t playing well enough to apply any pressure.”