Lionel Messi is a doubt for Barcelona’s opening Champions League clash against Celtic next week with a groin injury.

Messi aggravated the injury on his return to international football with Argentina last week, where he scored the winner in a World Cup qualifier against Uruguay.

The five-time World Player of the Year was supposed to feature in Argentina’s next qualifier against Venezuela on Tuesday but instead returned to Catalonia where he underwent scans over the weekend.

Barcelona said in a statement on Monday: “Tests conducted today on Leo Messi have confirmed that the player is still having trouble with the left adductor muscle.

“He has been recommended to lighten his training load over the next few days and his availability will depend on how the issue progresses.”

Messi has played down the injury and wrote on Facebook: “Everything is fine, I have to slow things down as I recover with physio, but it’s nothing to worry about.”

Argentina boss Edgardo Bauza said Messi had gone against the wishes of Barcelona’s doctors to make a triumphant return to the national team having dramatically reversed his decision to retire from international football.

Barcelona play Alaves in La Liga this weekend before hosting Celtic in their Group C opener on Tuesday.