Real Madrid have confirmed that winger Gareth Bale aggravated his calf injury during Sunday's thrilling El Clasico with Barcelona at the Bernabeu.
The 27-year-old was something of a surprise inclusion in Madrid's starting XI having been struggling with the problem in recent weeks.
Bale lasted less than 40 minutes before limping off and being replaced by Marco Asensio, and Madrid have now confirmed that he has done further damage to his previous injury.
"Following the tests carried out on Gareth Bale by the Sanitas Medical Services, the player has been diagnosed with a grade two injury in his left calf. His recovery will continue to be assessed," read a statement on the club's official website.
No timescale has been given for the Wales international's recovery, although he is expected to be sidelined for around a month, which would see him miss both legs of Real's Champions League semi-final against Atletico Madrid.