Hannover 96 centre-back Mario Eggimann could have made his final appearance for the club after suffered an ankle fracture during the 2-1 victory against Wolfsburg at the weekend.
The Swiss defender, in the final six months of his contract, had to be substituted after only 32 minutes on Saturday after an unfortunate challenge with Wolfsburg's Fagner.
"I instantly knew something was wrong," Eggimann said. "I just hope that's not the end to my season."
On Sunday Eggimann underwent surgery to his ankle, and he will remain in hospital for a couple of days.
Hannover 96 general manager Jorg Schmadkte ruled out a January signing to compensate for the loss of the centre-back.
"[It is] difficult to find a quality player for only five months," he said.
Hannover have signed Arsenal defender Johan Djourou, 26, on a loan deal during the winter transfer period. With Christian Schulz, André Hoffmann and Karim Haggui, Hannover boss Mirko Slomka still has options in the heart of his defence.
Elsewhere, new Hannover left-back Sebastien Pocognoli, 25, ended his debut after only 34 minutes when referee Gunter Perl send the Belgian player off for kicking Fagner. He will now serve a three-match ban.
Despite playing most of the match with ten men Hannover secured and important three points which lifts them up to tenth in the table, one point closer to the European places.