Borussia Dortmund defender Nico Schlotterbeck was carried off on a stretcher with what seemed to be a severe ankle injury near the end of his team's loss to Barcelona in the Champions League on Wednesday.
It leaves last season's Champions League runner-up without any fit central defenders.
Schlotterbeck headed narrowly over the bar in the last action of the game as Dortmund lost 3-2 to Barcelona. He landed heavily and appeared to be in severe pain.
The referee blew for full time while Schlotterbeck was being treated and he was later carried off on a stretcher, covering his face with his hands.
Coach Nuri Sahin said Schlotterbeck was "obviously in low spirits" after the injury.
"I'm waiting for the diagnosis and then we'll see, but I've watched the footage, too, and it doesn't look so good," he told broadcaster DAZN.
Dortmund already had to partner Schlotterbeck with midfielder Emre Can in the center of defense for the game because of injuries to Niklas Süle, who is expected to be out for several months with an ankle injury, and Waldemar Anton, who has not played since Nov. 30 with a reported muscle tear.
Dortmund is sixth in the Bundesliga and plays Hoffenheim on Sunday before facing Wolfsburg on Dec. 22 in its last game before the winter break.
The defeat against Barcelona saw Dortmund, last year's finalists, drop to ninth place on 12 points with two matches remaining, with the top eight earning automatic qualification for the round of 16.
"I am fuming because we played well," Sahin said. "We have to win these games. We deserved more in the second half.
"I do not want to hear that we played a good game. There is no room for mistakes and we have to learn that. We keep up with these top teams but in the end I want to sit here and say 'we won the game.' That is the development we need."
Information from Reuters and The Associated Press was used in this story.
