SAMARA, RUSSIA - JULY 07: Martin Olsson of Sweden is challenged by Marcus Rashford of England during the 2018 FIFA World Cup Russia Quarter Final match between Sweden and England at Samara Arena on July 7, 2018 in Samara, Russia. (Photo by Ryan Pierse/Getty Images)
We’ve identified 13 players who are out of contract ahead of the 2019/20 season and could be targeted by the Teessiders.
Boro are desperate to add more pace and width to their squad and have been linked with the 26-year-old winger. Harris scored one goal in 13 Premier League appearances for Cardiff last season.
A Welsh international, Williams helped Charlton win promotion from League One last season. The midfielder, 25, has said he wants to stay at the Valley but is yet to sign a new deal.
A player Boro fans know well. Adomah, 31, helped the Teessiders win promotion from the Championship in 2016 and was also part of the Aston Villa side which reached the top-flight last term. However, he wasn't offered a new deal.
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A shortage of full-backs meant Boro had to play players out of position last season. Bidwell, 26, is established at Championship level after making 40 league appearances for QPR last term.
Centre-back probably won't be the main concern for Boro's new boss, yet the Teessiders were left a little thin at the back last term. Barbet, 26, knows the Championship well after making over 100 league appearances for Brentford.
Another player who has been linked with Boro in the past. A Danish international, Knudsen, 26, possesses plenty of experience following his time at Ipswich.
The former Manchester United academy product has seen his career stall after being released by Hull. Keane, 26, did impress during a recent loan spell at Ipswich last season.
A regular in the Championship for Reading two years ago, the midfielder, 30, has struggled for game time at Huddersfield in the Premier League.
The towering frontman scored 12 Championship goals for Millwall last term, only two less than Boro's top scorer Britt Assombalonga.
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.
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.
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.
Now 31, Hooper made just six league appearance for Sheffield Wednesday last season. Even so, the striker is a proven goalscorer at Championship level.