Barcelona captain Andres Iniesta faces a spell on the sidelines after he limped out of Tuesday's 2-1 Champions League win over Bayer Leverkusen.
Iniesta was replaced by Sergi Roberto during the second half of the Nou Camp clash after signalling to the bench he had a leg problem.
Barca, who are already missing Lionel Messi, Rafinha, Claudio Bravo, Adriano and Thomas Vermaelen through injury, have since confirmed the midfielder has suffered a hamstring problem.
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"FC Barcelona have released the diagnosis of the injury suffered by Andres Iniesta during the game against Bayer Leverkusen in which he had to leave the field in the 60th minute," Barca said on their website.
"As such, the medical release states that the Barca midfielder has a hamstring injury in his right leg. His recovery will dictate his return to training."
Barcelona manager Luis Enrique described the injury to Iniesta - which follows the news that Messi is likely to be sidelined for up to two months - as "terrible news".
"These are thorns in our side we have to shake off," Enrique said.
"My players deserve a huge amount of credit for turning around a very difficult situation."
Barcelona's victory moves them to the top of Champions League Group E with four points from their first two matches after an opening draw at Roma, but the top three sides are separated by a single point.
"It is always tough to overcome the kind of pressure Bayer put on us tonight," Enrique continued.
"I said when we were drawn in Group E that it was a tough group. I'm really happy for the win. It's time to celebrate with my family, and on to the next one."
Iniesta looks certain to miss the weekend trip to Sevilla, along with Spain's Euro 2016 double-header with Luxembourg and Ukraine.