Cape Town - Karl-Heinz Rummenigge says Jerome Boateng needs to "come back to earth" following a poor performance as Bayern Munich were beaten 3-2 by FC Rostov.
As a result of their Group D Champions League loss, Bayern will have to settle for a second place finish behind Atletico Madrid.
With one game yet to play, the Bundesliga giants are on nine points from five games, with Atletico on 15.
Rostov (4) and PSV Eindhoven (1) make up the four-team group.
Boateng was far from his best, and looked sluggish in defence for Bayern and was at fault for Rostov's first goal ahead of conceding a 49th penalty as he fouled Christian Noboa in the box.
Douglas Costa had opened the scoring before an equaliser from Sardar Azmoun.
Dmitriy Poloz's spot kick put the Russian side in the lead, and despite Juan Bernat levelling minutes later, Noboa smashed home a second-half free-kick - although by that stage Boateng had been replaced by Mats Hummels with a reported thigh injury.
After the game, the Bayern Munich chairman told Sky Sports: "It stands out a little bit. Jerome needs to find a bit more calm again.
"I think it is too much for him since the summer. It would be for the benefit of him and the benefit of the club if he could come 'back to earth' a little bit."