Lionel Messi was forced off just before the hour mark of Barcelona's LaLiga clash with Atletico Madrid on Wednesday.
The Argentina star pulled up in discomfort after shrugging off pressure from Atletico captain Diego Godin early in the second half.
Messi attempted to play on but was eventually substituted for Arda Turan.
Initial concerns are that Messi may have suffered a recurrence of the groin injury he picked up while on international duty with Argentina, though it was unclear whether he may also have taken a knock to the back of his leg when attempting to sprint clear of Godin.
The 29-year-old's withdrawal occurred just eight minutes after Sergio Busquets was taken off for Andre Gomes, though it was unclear if the Spain international had also sustained an injury.
Barca were leading 1-0 at the time of Messi's exit, but Angel Correa struck an equaliser for Atleti just two minutes later.
