Lionel Messi suffered an injury on his first start of the season in Barcelona's narrow win over Villarreal at the Nou Camp.
Messi, who had recovered from a calf injury to feature, was replaced at the start of the second half after suffering a thigh problem.
The Argentine, making his 400th La Liga start, provided the corner for Antoine Griezmann to head home off the bar before Arthur made it 2-0.
Santi Cazorla pulled a goal back.
After the game, Barca boss Ernesto Valverde described Messi's injury as a "small problem in the adductor".