Pantilimon, 28, initially made his name in his native Romania with Politehnica Timisoara, but made his big move to Manchester City in 2011.
The giant, 6ft 8in goalkeeper has been a regular for Sunderland since that move, but he has now lost his place in the side under Sam Allardyce, with Vito Mannone and now Jordan Pickford preferred between the sticks.
Now third choice at the Stadium of Light, Pantilimon has become something of an outcast in recent weeks - and a January exit looks almost inevitable.
The Daily Mail are reporting that Watford are closing in on a deal for Pantilimon, with the goalkeeper undergoing a medical, but the Hornets could receive late competition from La Liga outfit Espanyol, even though their progress could prevent a move to Spain.
The Chronicle report that new Espaynol manager Constantin Galca is a huge fan of fellow Romanian Pantilimon, and could pursue a deal this month given that loan goalkeeper Francesco Bardi will return to Inter Milan at the end of the season.
Pantilimon's possible exit would give Sunderland some funds to work with in the transfer market, whilst cementing talented youngster Pickford as the club's first choice goalkeeper.