TULSA, Okla. -- Being young is certainly no barrier to winning at the U.S. Amateur.
"I never thought about that," said An, a 17-year-old who beat Stanford junior Steve Ziegler in 21 holes in Friday's quarterfinals. "I didn't know I could make it this far, because I was playing bad before. ... It would be awesome if I win, but I'm happy winning tomorrow's match to get in the Masters."
Last year's champion, Danny Lee -- 18 years and one month old at the time -- broke Woods' record by just under seven months. Now, An's hoping to break it again.
He won't turn 18 until Sept. 17.
An's opponent on Saturday will be Fresno State sophomore Bhavik Patel, who defeated Clemson senior Phillip Mollica 1 up.
Texas senior Charlie Holland defeated Oklahoma State sophomore Peter Uihlein in 19 holes to reach the other semifinal against fourth-seeded Ben Martin, who finished his college career at Clemson last year. Martin beat Arkansas senior David Lingmerth 2 and 1.
An squandered a 3-up lead on the back nine, bogeying the 17th and 18th holes to let Ziegler force a playoff. It was the second straight day that Ziegler was 2 down as he arrived at the 17th hole, only to win the last two holes.
An prevailed when Ziegler missed the green with his second shot at No. 3 and An followed by leaving his right in the middle of the green. When Ziegler missed a long par putt, he flipped his putter into the air and swatted at it before removing his cap to shake An's hand.
"I'm pretty happy obviously because it's quite an accomplishment to get this far in the tournament," said Ziegler, who will be exempt at next year's event by reaching the quarterfinals. "There are a lot of guys who went home unhappy a lot earlier. But then again, it's a lot of mixed emotions because I know I had a chance to do something pretty special."
Sports success runs in An's family. An's father, his caddie this week, and mother both won Olympic medals in table tennis in the 1988 Seoul Games. Not quite a decade later, An was 6 and following his dad around at the driving range when he tried golf.
"I guess I had nothing to do that day other than just hit some shots," An said. "I think my dad liked it. He liked my swing."
He started playing tournaments at age 7 -- "I wasn't that good," he admits -- and developed enough that 3½ years ago, he and his father moved to Florida to take advantage of the top-notch golf facilities. He was the runner-up at this year's American Junior Golf Association Rolex Tournament of Champions and a quarterfinalist at the Western Amateur before qualifying for the U.S. Amateur earlier this month.
If not for the tournament, he'd be in school this week at Bradenton Preparatory Academy -- and he's got another tournament next week.
"I'm missing the first two weeks of school. Pretty bad," he said.
An conceded that he was impressed when he looked around at the range earlier this week and saw top-ranked amateurs like Rickie Fowler and Morgan Hoffman. Now, he's outlasted both -- and just about everyone else, too.
"I don't have to feel different than them. We're the same golfers," An said. "They're better players than me, but we all qualified for this tournament, so I think we all have the same golf ability."