The Stoke forward, now on loan at Mainz, scored his first Bundesliga goal in the 2-2 draw at Bayern Munich on Saturday.
Bundesliga leaders Bayern ended a bad week in which they were knocked out of the Champions League by Real Madrid with a disappointing performance, the stalemate giving RB Leipzig the chance to cut the gap at the top to six points by beating Schalke on Sunday.
Thiago Alcantara denied Mainz a win that would have boosted its survival hopes, but Bayern could not complete the comeback and has the added worry of a David Alaba injury to deal with ahead of Thursday's (AEST) DFB-Pokal semi-final with Borussia Dortmund.
"I am sure it will be better against Dortmund on Wednesday".
"He couldn't continue. He had a small problem in the knee, which we are now checking, but it's not a big problem", said Bayern's Italian coach Ancelotti.
Mainz took the lead just three minutes after kick-off at the Allianz Arena when ex-Barcelona midfielder Bojan Krkic fired home his first goal for Mainz and stun the home crowd.
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Mainz were immediately punished as Bayern countered and Franck Ribery set up Robben to fire home left-footed.
Bayern's goalkeeper Manuel Neuer is sidelined with a foot fracture for the rest of the season and his replacement Sven Ulreich could not stop Daniel Brosinski's penalty on 41 minutes that put Mainz 2-1 up at the break.
Bayern finally made their 75 percent possession count with Thiago equaliser from 17 metres out. Hamburg is only a point above the bottom three.
Vedad Ibisevic's 12th goal of the season gave Hertha Berlin a 1-0 win over VfL Wolfsburg to stay on course for a Europa League spot in fifth place on 46.
Second-bottom Ingolstadt are five points from safety after a 4-2 defeat at home to Werder Bremen, despite leading 2-1 with nine minutes to go.