Rudy Gestede, Jonny Howson, Daniel Ayala, Marvin Johnson, Ryan Shotton and George Friend will all see their deals expire in the next few months – while there’s also uncertainty about Aynsley Pears’ situation. Scroll down and flick through the gallery to see how Boro could line-up if the aforementioned players move on:
5. LB: Hayden Coulson
After breaking into the first-team in pre-season, Coulson has been one of Boro's best performers this campaign. Photo: Alex Davidson
6. CM: Paddy McNair
Still only 24, McNair has been a key player for Boro this season after returning to a natural midfield role. Photo: Mike Hewitt
7. CM: George Saville
After a difficult start, the Northern Ireland international has improved this season. Adam Clayton and Jonny Howson are both out of contract this summer, which may give Saville has more responsibility at Boro. Photo: James Chance
8. LW: Marcus Tavernier
The versatile midfielder has stepped up his game this season, operating on the wing or in the middle of the park. Photo: James Chance