Manchester City are actively monitoring Toby Alderweireld's contract situation at Tottenham, sources close to the player have told ESPN FC.
Alderweireld's agent has fuelled speculation over the Belgium international's future by claiming the club must offer improved terms or let him leave, with several sides ready to sign him.
After months of negotiations, talks over an extension to Alderweireld's current contract, which ends in 2019, have stalled.
The player's current deal contains a clause that says if Spurs trigger a year-long extension in 2019, the defender can leave for a fee of £25 million.
News of Alderweireld's contract stalemate has alerted City, who are long-term admirers of the former Atletico Madrid man.
City boss Pep Guardiola was looking to strengthen his central defensive options over the summer, but failed to bring anyone in before last week's transfer deadline.
He could make a move for a new centre-back a top priority in January when the transfer window reopens, and Alderweireld figures on his wanted list.
Spurs would be loath to lose the 28-year-old, but if they are not able to agree a new deal with they could be reluctantly forced to consider offers for the player.
Mauricio Pochettino said on Aug. 25 that Tottenham would start contract talks with Alderweireld after the transfer window closed.
"Today, I was talking for one hour with Toby," Pochettino said. "He is so happy here. The club now is so busy trying to add more quality to the team.
"No doubt, when the window finishes, Daniel [Levy] will try to work and make happy every single player of the club."