Sunderland have made enquiries for Everton pair Bryan Oviedo and Darron Gibson.
Ronald Koeman is reluctant to lose Oviedo though the Costa Rica international is eager to leave and play regular football.
The 26-year-old joined the Toffees from FC Copenhagen in 2012 but has struggled with injuries throughout his career at Goodison Park, including a double leg fracture in an FA Cup fourth-round tie at Stevenage in 2014.
Gibson, meanwhile, has failed to make a competitive appearance for Everton since May last year and looks certain to leave the club, despite signing a new two-year contract last summer.