Reports in South America had suggested Estudiantes have accepted a club-record bid from Latics for the Argentinian hitman.
Martinez, though, says such talk is premature.
"At the moment, everything is still up in the air with that one," the Spaniard revealed to the Wigan Observer. "It is true he is a player we have been following for a long time, but I can't confirm anything regarding an offer."
Birmingham and Sunderland are also reportedly interested.
"Over the next few weeks we hope to finalise a few things with the players we have been trying to get, Martinez added.
"Mauro is one of a number of names that will come out because we have been following a lot of players."