Borussia Dortmund could be without Marco Reus for the Bundesliga derby against Schalke after he picked up a groin injury in a 4-0 Europa League victory over Qabala.
Reus opened the scoring after 28 minutes of the Group C fixture, but did not appear for the second half.
Dortmund went on to win the game comfortably to seal their place in the knockout stages of the competition with two group games to spare.
However, that joy was tempered by the loss of Reus, with head coach Thomas Tuchel unsure if he will be fit for Sunday's showdown against their rivals.
"It's possible that he misses the next match and it's possible that he plays," said Tuchel.
"Marco has had his foot on the ball, when he lost his balance during a tackle. He then felt a tear in his groin area.
"He continued to play, but came to the bench immediately after his goal. This happened before the goal. He wanted to finish the half.
"It's in a different area than the problems he had before. There is definitely a cause for concern. It is not certain if he can play on Sunday."
Despite potentially being without Reus, Tuchel is excited about the prospect of going up against Schalke for the first time since taking charge.
"I look forward to it very much," he added.
"There have been quite a few special moments, such as the first home game against Gladbach, with a positively charged atmosphere.
"I can imagine that it is even [more special] when the derby is pending."
