Mathias, one of Paul Pogba's brothers, has admitted he wants the Manchester United midfielder to sign for Barcelona.
Pogba is being linked with an exit from Old Trafford this summer.
The 28-year-old's current contract with United runs until the summer of 2022.
It is believed that the club will either extend his deal at the end of the season or sell him off, so he doesn't leave as a free agent next year.
Mathias, speaking to El Chiringuito, said: "Once he wins the Europa League, then we will talk."
When pressed further on supposed interest being shown from Catalunya, he added: "I don't know anything but I'm with you, I would sign tomorrow if that was the question.
"Hopefully he will sign for Barca."
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