Real Madrid midfielder Mateo Kovacic could be out of action until November after suffering a partial adductor tear.
Kovacic suffered the injury during Real's 3-0 Champions League win over Apoel Nicosia on Wednesday and was substituted in the 25th minute.
"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," a Madrid statement said.
AS reported that the 23-year-old could be out of action for at least six weeks, meaning he would miss eight matches.
The Croatia international would also sit out next month's World Cup qualifiers against Finland and Ukraine.
Kovacic has joined Karim Benzema on the injured list, with the France international striker sidelined for a month with a hamstring problem.
Meanwhile, Madrid head into Sunday's game at La Liga leaders Real Sociedad without the suspended Marcelo and Cristiano Ronaldo.