U.S. coach Bob Bradley will call in more than 23 players when the Americans start their final training camp ahead of the World Cup.
Team spokesman Michael Kammarman said Thursday that more than 23 would be called in, but it hasn't been decided exactly how many players will be brought into the camp.
FIFA requires each team to submit a 30-man preliminary roster for the World Cup by May 11. The U.S. camp opens May 15.
Several regular national team players recently have returned from injuries or hope to return soon. The camp will be used by the coaching staff to evaluate their progress.
The U.S. has exhibitions against the Czech Republic on May 25 and Turkey on May 29 before leaving for South Africa.
The Americans play Australia on June 5 at Roodepoort, one week before their World Cup opener against England in Rustenburg.
Teams must submit 23-man World Cup squads by June 1, and those players must come from the preliminary 30.
A team may make substitutions to cover injuries until 24 hours before its opener, and replacements don't have to be from the preliminary list.