SEOUL, South Korea -- Washington Wizards guard Gilbert Arenas strained his groin during practice Monday and won't play for the United States at the world championships.

"We know Gilbert is really disappointed," team managing director Jerry Colangelo said. "He's done a great job. It's an unfortunate situation, but he is not going to be able to continue on."

With Arenas out, the U.S. must cut one of its 13 remaining players before the world championships. The Americans play South Korea in an exhibition game Tuesday and open the worlds against Puerto Rico on Saturday in Sapporo, Japan.