Schalke have confirmed that Benedikt Howedes and Julian Draxler will be out until after the mid-season break due to hamstring injuries.
The duo both limped off during the Bundesliga outfit's 2-0 UEFA Champions League win over Basel on Wednesday, a victory that secured Jens Keller's men's place in the last 16 of the competition.
Captain Howedes lasted less than half an hour into the game as he was withdrawn after picking up the injury in a challenge with striker Marco Streller.
Draxler was able to have more of an impact as he scored the opening goal six minutes after half-time.
However, 15 minutes later the 20-year-old was also replaced after picking up what has now been confirmed as a tendon tear in his left hamstring.
The pair join a number of first-team players on a lengthy injury list, which includes striker Klass-Jan Huntelaar, midfielders Marco Hoger and Anthony Annan and defender Dennis Aogo.
Yet, there was better news on Japan defender Atsuto Uchida, who played the full game, despite suffering a cut to his right leg.
Uchida - in his fourth season with Schalke - is expected to be fit for the visit of Freiburg on Sunday after skipping Thursday training.