Paris St-Germain forward Kylian Mbappe suffered a “serious right ankle sprain” in his side’s French Cup final victory over Saint-Etienne on Friday.
Mbappe left the pitch in tears after being fouled by Saint-Etienne defender Loic Perrin in the first half.
PSG say the injury will be re-evaluated in 72 hours by a doctor.
The Paris club face Lyon in the French League Cup final on 31 July and then Italian side Atalanta in the Champions League quarter-finals on 12 August.
Should PSG progress, the Champions League semi-finals take place on 18-19 August, before the final on 23 August.
The France international, who has scored 29 goals in 33 appearances for the club this season, later returned to the dugout on crutches after Perrin’s foul, which led to a melee on the pitch.
Kylian Mbappe had scored six goals in his last four PSG appearances before football was suspended because of the coronavirus pandemic in March.
It was the first match in France since the league was ended in April, with PSG awarded the title.