Real Madrid say forward Lucas Vazquez and midfielder Mateo Kovacic will be sidelined for an undetermined period because of injuries sustained during the Club World Cup.
Madrid issued the medical reports on Thursday, 11 days after the team defeated Japanese side Kashima Antlers 4-2 in extra time in the tournament final.
Vazquez, who played 81 minutes of the final, has a muscle injury in his right leg.
Kovacic twisted a ligament in his left ankle while playing as a substitute in the closing minutes.
Both players have earned a place this campaign in Zinedine Zidane's starting XI, with Vazquez taking over from Gareth Bale after the Wales forward injured his right ankle in late November.
Madrid's next match is at home to Sevilla in the first leg of their Copa del Rey round-of-16 tie on Jan. 4.