Underarm serves are perfectly legal in tennis, yet they are frowned upon. But why? When an opponent is standing deep and far behind his baseline, why not surprise him with an underarm serve. It is often viewed as “not in the spirit of the game”.

Players who use the underarm serve often get booed by fans. An underarm serve may look simple but a good underarm serve relies on disguise and surprise. But in terms of tactics, It’s no different from a short cross-court forehand or a drop shot.

What do top players think of the underarm serve?

When asked about the underarm serve, Federer said:

Underarm is definitely a tactic, I believe. Especially when guys are hugging the fence in the back. From that standpoint, you shouldn’t be ashamed if you try it out.

You just look silly if you miss it sometimes. Why not try it? The problem is in practice, you never really try it. When you come out in the big stage in front of a full crowd, it is tricky to pull off.

Here’s Nadal’s opinion on the issue.

If you do it with the goal to improve your game, or like a tactical thing, I support 100 percent. If you do to disrespect the opponent, is not a good thing.

Everybody knows internally if you are doing in a good way or in a bad way. For me is no discussion about that. Is part of the rules, you can do it 100 percent. Is about yourself, if you feel good doing or not. Depends.