Sunderland's Younes Kaboul and Lee Cattermole look dejected
The defender only joined the Wearside club last summer in a £5 million deal from Tottenham Hotspur.
He initially struggled at the Stadium of Light, but improved under Sam Allardyce after he replaced Dick Advocaat early on in the campaign.
Chelsea's Diego Costa in action with Sunderland's Younes Kaboul
He went on to become a key player in the side as a result, forming a partnership with Lamine Kone in the centre of defence during the second half of the campaign.
New Sunderland boss David Moyes had hoped to keep him, but he now appears to be heading for an exit as the Guardian report that Watford are confident of signing him.
Sunderland's Younes Kaboul in action with Manchester City's Bacary Sagna
According to the newspaper, his exit looks likely after he told the club he wants to return to the London area.
It is understood that he has been offered a three-year deal at Vicarage Road to become a part of Walter Mazzarri’s side.
It now remains to be seen if the reported £4 million is a price that Sunderland will accept, or if they will push for a better deal before sanctioning Kaboul’s exit.
Lamine Kone celebrates scoring the third goal for Sunderland with Younes Kaboul and Jermain Defoe