Virtua Tennis 2009

Go onto quick match and choose to play a match on the clay court. Change it so that the top half is serving and put the settings to create the shortest game. Then you dont have to do anything, start the game, and do something else but look back at your xbox to restart the game. ( It doesn't matter if you loose). You can check how many more games you need to play in the stats.

For those with a turbo controller, this can be idled.
Set Game and Match to 1 on exhibition
Paris is an clay court
Set AI to Very Easy

Start match and Turbo A button. You will win most games and progress on other misc achievements. Game will continue to rematch. Back out when earned and repeat for other courts.
It took about 5hrs from 0-100 games played.