Why do tennis players have to choose the balls before they serve?

Question

Like for example.. the tennis player gets three balls from the 'ball boy', then he chooses are gives one back.. then only keeps two.. why?

Answer 1

You are only allowed to serve two (2) balls, that is why they have to return all other balls in their hands. Also, most players want to use balls whose felt are still thick and not thinned out and are not yet flat. Professional players hit the ball so hard on serves that balls tend to crack and easily loose their bounce.

Answer 2

The goal is to choose the newest possible ball.

The ball with the least amount of fuzz or the most amount of wear often gets tossed back to the ball kid.

Some players are superstitious and they like to play with the same ball they just won a point with.