I observed chappan and I think he does not have the game to beat the top 10 or 20 players anytime soon. I find him straining a lot for his ground strokes. Even his serve style needs to be improved. He swings his shoulders a lot. If he has any chance to win against top players he must do something about this. Other than Bjorn Borg I have not seen anyone else winning a top tennis match just playing ground strokes.
