Paris St-Germain express Brazil forward Neymar has "hyper-extended his lower leg" and endured "some tendon harm".
The 31-year-old got the injury in the last part of his side's success against Lille at the end of the week and was stolen away on a cot.
PSG added Neymar would "go through additional tests toward the beginning of the following week".
The French champions will try to upset a 1-0 shortage at Bayern Munich in the second leg of their last-16 Champions League tie on 8 March.
Neymar has scored 18 objectives and enlisted 17 helps for PSG this season, with two objectives and three helps coming in the Champions League.