Barcelona attacker Dani Olmo is a major doubt for the Clásico against Real Madrid at the end of the month after sources told ESPN he is likely to be sidelined for up to three weeks.
Olmo, 27, left the Spain squad last week with the problem, missing the World Cup qualifiers against Georgia and Bulgaria, to return to Barcelona for tests.
Barça subsequently confirmed a "muscle injury in Olmo's left calf" on Monday but ruled out any serious damage.
The Catalan club say his "recovery time will be dictated by his progress," with sources telling ESPN he is expected to be sidelined for two to three weeks.
Therefore, he will miss Saturday's LaLiga game against Girona and Olympiacos' visit in the Champions League next Tuesday.
Barça then travel to the Santiago Bernabéu on Oct. 26 for the first Clásico of the season against early pace setters Madrid, with Olmo unlikely to have recovered in time for that match.
It's the latest in a string of niggling injuries he has suffered since signing from RB Leipzig in a deal worth around €65 million ($75.2m) last summer.
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He missed a total of 20 games last season with various fitness issues, although still managed to make 39 appearances, scoring 12 goals, in his debut campaign with the Spanish champions.
In better news for Barcelona, Lamine Yamal and Fermín López both returned to training on Monday, while Ferran Torres is expected to be fit to face Girona despite dropping out of the Spain squad on Monday.
Yamal missed the loss to Sevilla with a groin injury before the international break, while López has sat out the last four games, also with a groin issue.
Torres, meanwhile, has returned to Barcelona and will miss Spain's match against Bulgaria on Tuesday.
Barça say the forward has "soreness in his left hamstring but no injury" and is not set to miss any games.