Virtua Tennis 4

To add to other guides, if you'd like to know how many of the 100 volleys your upto on your main screen go to 'My club' and click on medals and that will show you all your stats towards your achievements.

A volley is when you hit the ball before it touches the ground. Winning 100 points with volleys will come quicker when you play up close to the net. Smash the ball (also handy for the Power Smash! achievement) and have your opponents run back and forth trying to keep up and you should get this quickly.