Sidney Sam's comeback for Bayer Leverkusen lasted just a matter of minutes before he suffered a suspected muscle tear against Stuttgart.
Sam made his first appearance since picking up the same injury during Leverkusen's training camp in Portugal last month as a substitute in Saturday's 2-2 draw.
He left the field shortly after the problem surfaced with Leverkusen coach Robin Dutt fearing the worst.
"It does not look like it will be a short-term thing," Dutt said.
Sam's injury was one of several disappointments for Dutt, whose side conceded a late equaliser to pick up only a point.
"It was totally unnecessary to concede just before the end," he said. "We had managed to keep our organisation despite going down to ten men and we hardly let them have any chances, which makes this goal even more bitter."
For Stuttgart the win was a step back in the right direction after four straight defeats.
"It was a good team performance," director of sport Fredi Bobic said. "We more than deserved this point. It is also good that we had a bit of luck back on our side.
"This is the way the team has got to go. They were courageous today and, overall, we can build on this performance."