Valencia defender Antonio Barragán has become Boro's latest summer signing.
The 29-year-old has signed a three-year contract after completing a medical at Rockliffe on Friday afternoon.
Barragán, who signed for Liverpool as an 18-year-old, brings a wealth of experience, having made over 100 appearances for Valencia after spells with Deportivo La Coruna and Valladolid.
Head Coach Aitor Karanka was delighted to sign the right back.
"I am really pleased he has signed," said Karanka.
"He is a player we know a lot about and he is a good addition to the squad.
"He is a good lad, and he has played a lot of games for Valencia.
"He knows this country as well because he was at Liverpool as a young player.
"He is a good signing for us."
Barragán follows summer recruits Viktor Fischer, Bernardo Espinosa, Marten de Roon, Victor Valdes, and Jordan McGhee.