Sonic Tennis

Sonic Tennis is a mobile phone game released as part of the Sonic Cafe service offered by Sega. In this game you play as Sonic against Tails, Amy and finally Knuckles in a series of tennis matches. It's a best of three for each character, and once Knuckles is beaten you have won the game. High-scores won through in-game prize money can be uploaded to a server to compete across Japan. The original game was later replaced with a graphically enhanced version for newer phone models and Yahoo's Keitai service (formerly Vodafone).