Arda Turan is a doubt for Atletico Madrid's La Liga opener against Rayo Vallecano on August 25 after suffering a thigh injury in training.
The Turkish international suffered the problem during a training session on Wednesday, with Atletico releasing a statement shortly after.
"[Turan has suffered] a myofascial muscle injury grade II between the semitendinosus and biceps femoris at the middle third of the posterior aspect of the right thigh," according to a statement on the Spanish club's official website.
Atletico face Real Madrid in the Spanish Super Cup later this month before opening their league challenge, but Turan is suspended for that two-legged affair with Los Blancos.