Middlesbrough midfielder Grant Leadbitter has been linked with a return to the Stadium of Light.
The 31-year-old has a year left on his Boro contract with reports that Sunderland are looking to re-sign Leadbitter this summer.
Hard-working Leadbitter is captain of Boro but the Sun report he is likely to find game time limited this season under new manager Garry Monk and may have to move on for regular football.
Sunderland are reported to be keeping tabs on the situation.
Leadbitter started his career at Sunderland as a trainee and made 123 appearances before leaving for Ipswich Town in the summer of 2009.
After three years at Ipswich, Leadbitter moved back to the North East, joining Boro on a free transfer five years ago and has since gone on to make more than 170 appearances for the Teessiders.
Sunderland boss Simon Grayson has brought in seven new faces this summer and is still looking to bolster his squad before the transfer window closes at the end of August.
Signing another striker is a priority, with the club hopeful of landing Aston Villa forward Ross McCormack on a loan deal, while bringing in reinforcements to the centre of defence is another priority area for Grayson.
Sunderland are relatively well-stocked in central midfield with Lee Cattermole and Didier Ndong starting the season against Derby County, with Darron Gibson, Jack Rodwell and Paddy McNair the other options available to Grayson when McNair returns from a long-term injury.