MADRID: Barcelona coach Luis Enrique expects Lionel Messi to bounce back from a difficult summer with his usual enthusiasm -- and does not rule out a return to international football.

Messi and his father Jorge were given jail sentences by a Spanish court earlier this month for tax fraud, and the Argentina captain quit international football after his country lost to Chile in the Copa America final in June.

Asked about the 21-month sentence, which is currently suspended, Luis Enrique told a news conference: "I don't think it will affect Leo but he is the only one that can reply to that."

Messi announced his international retirement after missing a penalty in the Copa America final shootout.

But he expects Javier Mascherano -- also a Juventus target -- who is under contract until June 2018, to stay put.

"I hope that Mascherano's (contract) renewal is completed soon," he said. "I believe that will be the case. He is vital, key for our system, on and off the pitch."

However, Luis Enrique expects great things from Turkey midfielder Arda Turan, who joined Barca last summer from Atletico Madrid but only made his debut in January 2016 due to a transfer embargo on the club.

Turan found it difficult to earn a starting place, with just two goals in nine league games.

"The first year is always difficult," he said. "I fully trust Arda. Last year, he gave a lot and this year, his level will go up. I'm certain."