Originally Posted by
kagerou_zutsumi
Well that happens. Richard Gasquet, a pro tennis player, defeated a pro when he was just like 15 years old. And that's young for a professional tennis player.
I dunno about what happened in the anime but in real life, to be able to play in the US Open (or any popular international tennis event for that matter), which is one of the four tennis Grand Slams (the biggest events in the world of professional tennis), I think one should be a pro. So Ryoma should've been a pro when he played Hewitt. But that is just in the anime because he did not become a pro after the Kantou finals in the manga.
Again, I dunno if this is the case with the anime (because apparently, I did not watch the last episodes) but the US Open in real life is actually the last Grand Slam of the season. On the contrary, Wimbledon precedes the US Open by five or six weeks.