JERMAIN Defoe is almost certain to remain at Sunderland this January - due to bizarre clause in his contract.

SunSport believes the 34-year-old can leave the Black Cats for FREE if they are relegated at the end of the season.

Defoe will be allowed to leave Sunderland for free if they are relegated

Keep up to date with ALL the Sunderland news, gossip and transfers on our club page plus fixtures, results and live match commentary

But it is likely he will stay with relegation-threatened Sunderland to help them beat the drop.

But the former Tottenham and Portsmouth star would then be able to leave for free if they don't - meaning he can remain in the Premier League.

A source said: "West Ham want to sign Defoe, but the chances have dipped dramatically after details of his contract emerged.

4 Slaven Bilic is set to miss out on Defoe this January Credit: Reuters

4 The striker started his career at West Ham Credit: PA:Press Association

4 Hammers captain Mark Noble started following Defoe on Twitter in a bid to lure him to the London Stadium Credit: Reuters

"And there is little chance of him pushing for a move back home because he is in a win-win situation.

"There's no incentive for Sunderland to sell a player who carries their survival hopes and Jermain's people have cut a very clever deal."

The Hammers are ready to offer £6m for Defoe, but Sunderland boss David Moyes has made it clear he would reject any offers.

And hopes had risen at the London Stadium a deal could be struck after captain Mark Noble started following him on Twitter.

Sunderland are sitting third bottom of the Premier League ahead of the all-but-doomed Swansea and Hull.

And it is likely they will beat the drop because of Defoe's goals, as he has netted seven in 16 this season.

He is under contract at the Stadium of Light until the age of 37, and is a firm favourite with the fans.