Lionel Messi reportedly took painkillers in the build-up to El Clasico after suffering an ankle injury on Thursday.
The Barcelona attacker failed to make his mark at the Bernabeu, as Real Madrid came from behind to beat the La Liga leaders 3-1 in the capital.
According to El Confidential, Messi's muted performance was due to a knock that he picked up prior to the match.
The Argentine managed to partake in the contest due to a painkilling injection, but the sprain harmed Messi's overall display.
The defeat was Barcelona's first in the league this season.