Real Madrid midfielder Luka Modric has undergone knee surgery on a cartilage problem, the LaLiga club has confirmed.

Modric completed 90 minutes in Thursday's (AEST) 2-2 UEFA Champions League draw against Borussia Dortmund but was left out of the squad for Monday's match with Eibar because of his injury.

"Our player Luka Modric has undergone successful arthroscopic surgery in his left knee for removal of a patellar chondral fragment of post-traumatic origin," a statement released by Real Madrid said.

"Modric will begin his recovery work from tomorrow."

Madrid did not put a timescale on the rehabilitation process but Modric would seem certain to miss Croatia's forthcoming FIFA World Cup qualifiers against Kosovo and Finland.

The 31-year-old's setback further stretches Zinedine Zidane's central midfield resources, with Casemiro currently recuperating from a fractured left leg.