Guan, who opened with rounds of 66-64 to build a five-shot lead, finished at 15-under 273. He felt the pressure toward the end of the final round after a bogey on the 16th hole. But he handled the island-green 17th with a par, and then clipped a 60-degree sand wedge for his 5-foot par putt and the win.
Oliver Goss of Australia, a quarterfinalist at the U.S. Amateur, closed with a 72 to finish third. Hideki Matsuyama, Asia’s No. 1 amateur who was going for his third straight Asia-Pacific Amateur title, shot 68 and was five shots behind. Matsuyama made the cut at the Masters the last two years.
‘‘I'm so excited,’’ Guan said. ‘‘I'm really happy to become the youngest player at the Masters and looking forward to going there. I don’t know what’s going to happen there, but I know I just want to do well.’’
Guan added to what already has been an historic year at Augusta National, which in August invited Darla Moore and Condoleezza Rice to become the first female members in its 80-year history. In April, there will be two women in green jackets, and an eighth-grader from China trying to win a green jacket.