Messi will be monitored and assessed daily with the extent of the damage to an abductor muscle in his thigh not fully known.
A calf injury had seen Messi miss Barcelona’s first four games of the season.
“First team player Leo Messi has an elongation at the adductor of the left thigh. It is low and its progression will determine his availability,” the club statement said.
The 2-1 win over Villarreal was Messi’s first start of the season, having returned to action with half-an-hour from the bench against Borussia Dortmund in the Champions League.
He also came off the bench against Granada.
Messi scored 51 goals for Barcelona last season, and this week won Fifa’s Best Men’s Player award ahead of Cristiano Ronaldo and Virgil van Dijk.
Barcelona have been boosted by Messi’s return to fitness, as well as that of Ousmane Dembele, who had been out with a hamstring injury since the opening game of the season.
The win over Villarreal leaves Barcelona fifth in La Liga, four points behind leaders Real Madrid.
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