Borussia Dortmund defender Sven Bender faces a spell on the sidelines after suffering an ankle injury in the 6-1 friendly win at Paderborn on Tuesday.
Dortmund coach Thomas Tuchel told reporters he believed the injury "doesn't look good."
Bender, 27, only returned to the BVB squad late last year after recovering from an injury picked up at the Olympics.
Ahead of the restart of the Bundesliga season at the weekend, Tuchel identified Bender as one of the team's leaders, telling ESPN FC's Raphael Honigstein that he's a "big personality in the dressing room."
Bender was substituted with the injury only 11 minutes into the game and Tuchel told reporters: "It doesn't look good. His ankle swelled up straight away.
"I am guessing now, but it looks like a capsular or ligament injury at least."
Bender, who sustained the injury in a late challenge by Paderborn's Sven Michel, was taken to hospital for tests.
"I hope that it won't be a long-term injury, but when Manni [Bender] screams in pain, then it is not a good sign," club captain Marcel Schmelzer said.
"We will probably have to do without him for a few weeks."
