Ribery injures ankle at Hoffenheim
Ribery helped end Bayern's league goal drought stretching back to August 20 when he weaved into the area and saw his curled drive palmed away by goalkeeper Daniel Haas, only for Thomas Muller to tuck away the rebound just past the hour.
The club said the French international had twisted his ankle following his shot on goal but it was unclear if, or for how long, the midfielder would be out of action.
"I think his injury may be quite serious," Bayern coach Louis van Gaal told reporters.
Club director Karl-Heinz Rummenigge said first medical checks showed the injury could be worse than just a sprained ankle.
"The first diagnosis does not look good. He could be out for a longer time," Rummenigge said, speculating that it could be ligament-related.
Bayern, who won their Champions League group opener at home to AS Roma last week, visit Basel in their next Group E game next Tuesday.
The German champions are also missing Dutch winger Arjen Robben, who aggravated a muscle injury at the World Cup, and could be out until late this year.