Sevilla are in advanced talks to sign Mariano, with a confidence that a deal can be closed on Tuesday morning.
However, AS says Sevilla intermediaries have learned Real are also keen on the striker, who left them only a year ago for France.
Real coach Julen Lopetegui wants a new No9 added to his squad before this week's transfer deadline and Mariano fits the bill.
Real enjoy first refusal on the player for a price of €40m. They also hold 35 per cent of Mariano's registration, meaning they would only have to pay €28m to re-sign the striker.