"We know Gilbert is really disappointed, he's done a great job," said team director Jerry Colangelo in a statement. "It's an unfortunate situation but he is not going to be able to continue on. We're concerned because he has had a history regarding groin pulls. This is a precautionary move but it is important that he return home and get treatment."
The team is practicing outside of Seoul, South Korea and is participating in the World Basketball Challenge, a two-game tune-up for the Worlds.
Arenas, a guard for the Washington Wizards, played in all four USA pre-World Championship exhibition games, started once, and averaged 3.8 ppg., 2.3 rpg. and 11.0 minutes a game.
His departure does help the team as they try to cut the roster down. His injury leaves just 13 players left for 12 spots.
Arenas was very vocal in his desire to represent Team USA. After a legal incident in the spring, Arenas apologized to various members of USA Basketball the next day, including Colangelo.
The 13 remaining finalists contending for the 12 man 2006 USA Basketball Men's World Championship Team roster include: Carmelo Anthony (Denver Nuggets); Shane Battier (Houston Rockets); Chris Bosh (Toronto Raptors); Bruce Bowen (San Antonio Spurs); Elton Brand (Los Angeles Clippers); Kirk Hinrich (Chicago Bulls); Dwight Howard (Orlando Magic); LeBron James (Cleveland Cavaliers); Antawn Jamison (Washington Wizards); Joe Johnson (Atlanta Hawks); Brad Miller (Sacramento Kings); Chris Paul (New Orleans/Oklahoma City Hornets); and Dwyane Wade (Miami Heat).
Information from USA Basketball was used in this story.