Germany manager Oliver Bierhoff has hit out at Chelsea over their treatment of midfielder Michael Ballack.
The former international striker has accused last season's FA Cup winners of denying Ballack permission to participate in an adidas promotional campaign.
"That is not how you treat a Germany player and in particular our captain," said Bierhoff.
"He is regarded highly throughout Europe and I am astonished by the way Chelsea have acted.
"It is absolutely not right that they act like this with us and adidas, who are also their partners, but it seems they have different methods at their club.
"We will certainly be going back to them to follow this up. Having direct contact and sharing our views is important and we will certainly be giving them our opinion."
Ballack is currently recovering from ankle surgery, and his absence from Chelsea's 23-man squad for the group stage of the Champions League intensified speculation linking with a move away from Stamford Bridge in the January transfer window.