Real Madrid have revealed that key midfielder Toni Kroos is facing a spell on the sidelines with knee ligament damage.

Kroos will miss Real Madrid's trip to Real Betis in La Liga this weekend, but the Spanish and European champions have not placed a timescale on the German international's recovery.

The 28-year-old is reported to have picked up the problem in the first half of Wednesday's 3-1 win over Paris Saint-Germain in the Champions League, but still went on to play the full 90 minutes of the last-16 first leg.

"Following tests carried out on Toni Kroos by the Sanitas Real Madrid Medical Services, he has been diagnosed with a sprained to the exterior lateral ligament in the left knee," read a statement on Real Madrid's official website. "His recovery will continue to be assessed."

Kroos has scored four times and provided seven assists in 29 appearances for Madrid this season.