Botafogo defender Doria looks to be on the verge of a switch to Marseille, with the youngster set to undergo a medical in France on Monday afternoon.
The highly-rated 19-year-old center back has been persistently linked with a move to Europe this summer and speculation has increased with Botafogo in the midst of a financial crisis that has seen a number of players go without wages.
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Vagner Mancini says the stopper, who was also attracting major interest from Lyon, Lazio and Valencia, will be sorely missed by the Rio de Janeiro club.
"He's a spectacular athlete, he's so much more than everybody thinks," Mancini told a press conference on Sunday. "He'll be soon be playing for Brazil. I am sorry he's leaving, we'll miss him very much. He's an unique talent. I wish him luck for his future career."
The under-20 international has made one appearance for the senior national team, appearing against Bolivia last year in a friendly for domestic-based players only.
He will cost the Ligue 1 club a fee in the region of 10 million euros, of which around Botafogo will receive €3 million for the 30 percent stake the club holds in his registration.