The Frenchman was withdrawn in the first half of Real Madrid's trip to Malaga after colliding with Cristiano Ronaldo and could now miss the crunch clash with Barcelona
The France international accidentally collided with Cristiano Ronaldo following a cross from Gareth Bale during the first half of the meeting at La Rosaleda.
Benzema was unable to continue and had to be replaced by Angel Di Maria, with the Frenchman suffering clear discomfort in his right leg.
Early indications suggest the damage was a minor impact injury, though Benzema will undergo further tests upon returning to Madrid to see whether or not he could miss next Sunday's home clash with Barcelona.
Ronaldo, who scored the opening goal for his side, was also left nursing a knock but was able to continue.
Speaking after the match, coach Carlo Ancelotti confirmed Benzema had suffered "a blow to the muscle" as the striker now faces an anxious wait ahead of next Sunday's encounter.
Madrid won 1-0 on the night against Malaga thanks to Cristiano Ronaldo's first-half strike.