Middlesbrough head coach Aitor Karanka has said defender Damia Abella could be ruled out with a knee injury he picked up in Tuesday's win at Cardiff City.
Abella, 32, joined Boro in the transfer window following his departure from Osasuna, and has since made seven appearances in league and cup.
However, the former Barcelona B and Betis full-back was withdrawn midway through the second half in Wales.
"I don't think it's going to be good news about him," Karanka told BBC Tees.
"We need to wait for the results of a scan, but it's very bad for me because he's an amazing lad and a good player who is helping us."
Boro are now eighth in the Championship, with 12 points accrued from seven league games.
The result in Wales means the Teessiders have won their last two games away from the Riverside, following the weekend win at Huddersfield.
"It was very important," Karanka said.
"With games away against a team in the highest positions at the end, it's a very good win to get us improving our confidence."