Jack Colback has reportedly informed Sunderland that he would like to leave the club this summer.
The midfielder is believed to have recently been offered a new contract by the Wearsiders, but the 23-year-old has decided to reject those terms.
With 12 months left to run on his deal at the Stadium of Light, Colback has decided that the time is right for him to take on a new challenge, according to the PA.
As a result, the Black Cats are expected to part with his services to avoid losing him on a free transfer next year.
Colback made 40 appearances in all competitions last season.
