Lionel Messi was withdrawn during the 2-1 win over Villarreal on Tuesday, in which Arthur and Antoine Griezmann were on target.
Barcelona have now revealed via their website that the 32-year-old has elongated his left adductor, but did not confirm when he will return.
The statement read: “First team player Leo Messi has elongated his left adductor.
“He is out and his recovery will determine his availability.”
Barcelona have endured a mixed start to the season, winning three and losing two of their opening six fixtures. The Catalan giants have struggled in the absence of their star player in recent years, and fans will be worried about Messi deciding not to extend his current contract. Spanish football expert Guillem Balague revealed earlier this month that he thinks Messi could continue playing until the 2022 World Cup in Qatar, but that he might quit club football before that.
“Messi will not be playing when he is 40,” said Balague told BBC Sport.
“He’s 32 and for the first time I have started hearing stories of people close to Messi saying ‘what if he only has two more years at Barcelona?’.
“I went into panic – ‘only two more years of Messi?’
“At the end of each season he decides whether he is fit or not.
“He’s got it in the back of his mind that he can perhaps play at the next World Cup.
“His contract at Barcelona finishes in 2021.
“The extra year between the end of that contract and the World Cup… does he play in the elite risking his body and his mind?
“Or does he step down and prepare himself for his last World Cup in 2022?”
Next up for Barcelona is a trip to play Getafe in the league before taking on Inter Milan in Europe.