Bremen want Brazilian midfielder Diego back in time for the new Bundesliga season which kicks off on August 15, while Schalke also want their Brazil star Rafinha. The clubs both appealed to CAS after arguing against FIFA's insistence that all players aged 23 and under must be released by their clubs for the Olympics.
"We are pleased with the decision, because we have worked closely with the clubs in this legal matter," said German Football League spokesman Holger Hieronymus. "It was always our opinion that under FIFA regulations we were not committed to allowing our players to go freely."
Both Diego and Rafinha travelled to Beijing against the clubs' wishes. The Olympics tournament begins on Thursday, when Brazil are set to face Belgium.
"FIFA failed to realize the legal implications of this decision early and the preparation of the clubs ahead of the new season has been affected," Hieronymus.
Despite the ruling, Argentina coach Sergio Batista said he intended to play Lionel Messi in Thursday's game against Ivory Coast despite Barcelona's insistence that the player return to Spain.