Striker Miroslav Klose has left Germany's Swiss training camp to fly home to Bremen for personal reasons.
Klose is a key to Germany's hopes
However, the Werder Bremen striker is scheduled to rejoin the squad before Tuesday's friendly against Japan.
His agent Alex Schuett told the SID sports news agency that Klose had returned home for "very private reasons" but refused to elaborate.
Germany's Chelsea midfielder Michael Ballack will not be risked against Japan because of his ankle injury.
The German squad will leave their Swiss base on Tuesday and set up their World Cup camp in Dusseldorf.