Ben Gibson will leave Middlesbrough in the summer if the club are relegated from the Premier League, Sky Sports News HQ understands.
The 24-year-old has been a standout performer for Boro in their first season in the top-flight since 2009 and was rewarded with his first senior England call-up in March.
Gibson signed a new five-year contract at the Riverside last August, but SSN HQ understands he has already attracted interest from a host of Premier League clubs ahead of the summer.
Boro have kept 10 clean sheets this season with Gibson at the heart of their defence, but their failings in front of goal have left them in 19th place, nine points from safety with only five games remaining.
Steve Agnew's side are the Premier League's lowest goalscorers, having netted only 23 goals, and despite their resilient backline, are without a win since December 17.
Boro, who host 20th-placed Sunderland on Wednesday, face a tough run-in with matches against Manchester City (H), Chelsea (A), Southampton (H) and Liverpool (A).