Aston Villa winger Adama Traore has joined the club in a deadline day move.
The 20-year-old becomes the club's 11th senior signing of the summer and has penned a four-year contract.
A former Barcelona youngster, Adama brings youthful experience to the club and Boro Head Coach Aitor Karanka was delighted welcome a player he knows well.
"He is another important player and I am expecting a lot from him," Karanka said.
"I've known him since he was a kid. He went into the national team just after I left, but I know all about him and what he can do.
"His level is higher than he showed last season, but in the right environment I'm hoping that he will show what he is capable of."
Born in Barcelona to Malian parents, Adama joined the Spanish club's youth setup as an eight-year-old.
Known for his direct style and explosive pace, the winger made his first appearance for the European giants aged 17.
The majority of his time with the Catalan club was with Barcelona B in the Spanish Segunda, where he enjoyed more than 60 outings and scored eight goals.
In August 2015, Adama joined Aston Villa on a five-year deal. He made just a dozen appearances for The Villains, scoring once, owing largely to an injury sustained during the New Year's Day clash at Sunderland last season.