Martin Sendoa says the Argentina international could return to his homeland this summer.
"Nicolas' desire is to retire in River, he is dying to play there," Sendoa told TyC Sports.
"He is well at [Manchester City], he is playing more than last year. But if River calls him and convinces him...in June it may happen.
"No leader has called me, they still have not made a move. Nicolas is not going to offer, he has to get the call from Gallardo. But one call would change everything."