Real Madrid midfielder Mateo Kovacic suffered a torn adductor muscle during Wednesday's 3-0 Champions League win over APOEL, the reigning Spanish and European Champions have confirmed.
Kovacic was making his first start for Madrid since last month's Supercopa de Espana win over Barcelona but was withdrawn after 25 minutes.
A club statement read: "Following the tests carried out on Mateo Kovacic, the player has been diagnosed with a partial tear of the adductor muscle tendon in his right leg.
"His recovery will continue to be assessed."
Madrid won 3-0 thanks to a brace from Cristiano Ronaldo before captain Sergio Ramos got on the scoresheet with an overhead kick.
Zinedine Zidane's side will look to get back to winning ways in LaLiga when they travel to Real Sociedad on Sunday, following back-to-back home draws against Valencia and Levante.
Ronaldo and Marcelo will miss out through suspension at Anoeta, while Karim Benzema (hamstring) will remain sidelined and Marco Asensio (leg) is a doubt.
