Derby County boss Gary Rowett has confirmed Sunderland are keen to sign Chris Martin - but says the striker has yet to decide on his future.
Black Cats boss Chris Coleman confirmed after their 1-0 win over Hull City today that they have a transfer deal in place for a player as they look to add much-needed reinforcements.
Coleman wouldn't reveal who the player is, but Rams chief Rowett confirmed Sunderland have made an approach for Martin.
Rowett said: "We have some strong interest in him, and Sunderland are one of those teams, but until the player decides he wants to go somewhere and signs on the dotted line, whether that is a loan or a permanent deal, then he is our player.
"If Chris wants to leave and he gets an opportunity to do so, then we will support that decision."
Sunderland are understood to have agreed terms on a loan deal but there is significant competition for the 29-year-old and the Black Cats will have to convince the Scotland international to make the switch to Wearside.
Personal terms have not yet been agreed as the striker weighs up his options.
Coleman said: "We thought that something was over the line but at the minute it is not.
"We have got a deal with a club and we are waiting for an answer and a decision from a player.
"I can't mention players or clubs but that is where we are. Until it is done I can't say yes I am super confident until it is done. I have been out of the transfer market for a long time, six years. "I think 'we've got it' but we haven't yet. Until I am saying 'yes, he is here' we are where we are."
Sunderland beat relegation rivals Hull 1-0 at the Stadium of Light to lift them off the foot of the Championship, Joel Asoro's 20th minute strike enough to seal three points.