Mats Hummels faces a fitness battle ahead of Tuesday's Champions League clash against Galatasaray after the Borussia Dortmund captain injured his foot in their 2-1 defeat at Bayern Munich.

The Germany centre-back limped off at half-time at Munich's Allianz Arena on Saturday.

Marco Reus' first-half header for Dortmund was cancelled out by Robert Lewandowski's second-half strike and Arjen Robben's late penalty for Bayern.

The defeat leaves Dortmund 16th in the league as they endure the worst start to a Bundesliga season in the club's proud history after seven points from ten games and five straight defeats.

In contrast, Dortmund have won all three of their Champions League games so far, including a 4-0 romp at bottom side Galatasaray last month to leave them top of Group D.

Another win over the Turkish giants at Borussia's Westfalenstadion on Tuesday will put Dortmund in the Champions League's knock-out phase, but Hummels faces a race to be fit.

"It doesn't look good," said coach Jurgen Klopp. "Mats limped past me in the dressing room with a bandage on his foot.

"He said he felt pain after jumping for the ball, we'll know more after a scan."