Arsenal face missing out on Atletico Mineiro midfielder Bernard.
The 20-year-old's agent, Adriano Spadotto, said Shakhtar Donetsk are also interested but the player's father claims Porto are in the driving seat.
"Nothing is decided yet," said his father, Delio Duarte. "We know there is an interest from Arsenal.
"There has been nothing official from the club. [Brazil striker] Hulk has convinced Bernard that a move to Porto would be better for him at this stage of his career."
Spadotto said: "He would prefer to join a middling but good club in Europe rather than risk joining an elite club like Arsenal and not getting much of a chance to play.
"Bernard has great interest in going to Porto."