Others who have departed are defenders Steve Cherundolo and Michael Parkhurst, midfielder Benny Feilhaber and forward Freddy Adu.
That leaves only 18 players in camp. Besides Feilhaber, six other players -- all Confederations Cup participants -- were eligible as stand-by players: Jozy Altidore, Conor Casey, Ricardo Clark, Brad Guzan, Sacha Kljestan and Jonathan Bornstein.
None is expected to play against the Canaleros on Saturday in Philadelphia.
UPDATED U.S. ROSTER:
GOALKEEPERS: Troy Perkins (Valerenga, Norway), Luis Robles (FC Kaiserslautern, Germany)
DEFENDERS: Jimmy Conrad (Kansas City Wizards), Clarence Goodson (IK Start, Norway), Jay Heaps (New England Revolution), Chad Marshall (Columbus Crew), Heath Pearce (Out of Contract)
MIDFIELDERS: Davy Arnaud (Kansas City Wizards), Kyle Beckerman (Real Salt Lake), Colin Clark (Colorado Rapids), Sam Cronin (Toronto FC), Brad Evans (Seattle Sounders), Stuart Holden (Houston Dynamo), Logan Pause (Chicago Fire), Robbie Rogers (Columbus Crew)
FORWARDS: Brian Ching (Houston Dynamo), Kenny Cooper (FC Dallas), Santino Quaranta (D.C. United)