Bayern Munich, already without striker Harry Kane, will have to do without two other key players, Kingsley Coman and Alphonso Davies, for an unspecified period with injuries, the club said on Sunday.
Examinations showed that both players suffered "muscle strains in the left hamstring" during Saturday's win over Heidenheim, the Bundesliga leaders said in a statement.
"Both players will be sidelined for the time being," it said, without specifying how long they will be out.
Coman, a 28-year-old French international winger, came on as a second-half substitute before leaving the pitch with a knock just before the end of the game.
Davies, a Canadian international full-back, finished the match.
Top scorer Kane missed Saturday's game with a right thigh injury.
Bayern face a potentially pivotal Champions League match against Shakhtar Donetsk in Gelsenkirchen, Germany, on Tuesday. Bayern are 13th in the first-round table. Only the top eight finishers qualifying directly for the knockout rounds.
Bayern are unbeaten in the Bundesliga after 13 rounds but were knocked out of the German Cup at home on December 3 by last season's double winners Bayer Leverkusen.