We’ve identified 13 players who are out of contract ahead of the 2019/20 season and could be targeted by the Teessiders.
9. Lee Gregory
The towering frontman scored 12 Championship goals for Millwall last term, only two less than Boro's top scorer Britt Assombalonga. Photo: Warren Little
10. Martin Olsson
The Swedish international hasn't played since before Christmas after rupturing his Achilles last term. Rangers and Nottingham Forest have already been linked with the full-back. Photo: Ryan Pierse
11. Conor Washington
After scoring for Northern Ireland at the weekend, Washington reminded everyone of his availability. The 27-year-old failed to score in 19 league appearances for Sheffield United last season though. Photo: Dan Istitene
12. Ryan Williams
The Aussie winger has been a regular for Rotherham in the last two seasons, first helping them win promotion from League One before last campaign's relegation. Photo: George Wood