BEIJING — Henry Cejudo, the 21-year-old wrestling prodigy who had wrestled in only one world-level senior tournament before Beijing, has won the Olympic gold medal in men's freestyle 55-kilogram wrestling.

Cejudo, crying the moment the match ended and wrapping himself in an American flag, defeated Tomohiro Matsunaga of Japan 2-2 on tiebreaker and 3-0 in the best-of-three match. Cejudo was 31st in last year's world championships, his only prior tournament at this level.

Cejudo, the son of undocumented Mexican aliens who bypassed a college career to try to become an Olympian, assures the United States of winning a freestyle wrestling gold for the ninth consecutive Olympics at which it has competed.

The bronze medalists were last year's world champion, Besik Kudukhov of Russia, and Radoslav Velikov of Bulgaria. Kudukhov was pinned by Matsunaga in the semifinals.