Grant picked Ballack ahead of Lamps for Tuesday's Champions League clash with Olympiakos.
And German legend Beckenbauer said: "Lampard is Chelsea's hero and, if Grant keeps playing Ballack over him, he will be fired in one week or so.
"Maybe there is a way for both of them to feature - one playing a bit more offensively and the other one a bit defensively.
"There must be a way. Somewhere on the pitch there should be a place for Ballack."