At the age of 17, Tokito Oda became the youngest world No. 1 in wheelchair tennis. At 18, he was an Olympic gold medalist.

Now, at 19, the Japanese prodigy is chasing a career Grand Slam at the U.S. Open — the only thing missing from his resume.

"He's like a standing player who just happens to play sitting down," said French wheelchair legend Stephane Houdet, marveling at the young left-hander known for his signature headband and ferocious game.