Canadian international Alphonso Davies suffered a strained knee ligament in Bayern Munich's 3-1 win over Borussia Monchengladbach on Saturday.
The left back went off in the 85th minute of Saturday's Bundesliga game after seeming to hurt his left knee.
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"He's twisted his knee and needs to be examined," Bayern coach Thomas Tuchel said. "I would have no words for it if this happens again as Phonzie is getting back to his form."
Following the game, Bayern released a statement saying that Davies had "suffered a ligament strain in his left knee" and "will therefore face a spell on the sidelines."
Davies was playing his 27th game of the season for Bayern in all competitions and had scored his first goal of the season in last week's 3-2 win over Augsburg. His time at Bayern has repeatedly been interrupted by injuries and illness.
Tuchel said Bayern hoped to have the injured defender Dayot Upamecano and midfielder Joshua Kimmich back in action for next week's game at league leaders Bayer Leverkusen. Neither has played since being hurt in Bayern's 1-0 win over Union Berlin on Jan. 24. Upamecano damaged his thigh muscle in that game and Kimmich injured his shoulder.
"We'll definitely try with Upa and Josh. That will be decided in the middle of the week," Tuchel said.
Upamecano's injury has meant more game time for new loan signing Eric Dier, who has played three matches since joining from Tottenham. The 19-year-old Aleksandar Pavlovic has come into midfield in place of Kimmich and scored in his last two games.
Bayern are also missing other players, including Konrad Laimer, Kingsley Coman and Serge Gnabry.
Information from the Associated Press and Reuters contributed to this report.