Middlesbrough have announced that Chelsea defender Kenneth Omeruo has completed a deal to return to the Riverside Stadium on loan.
The 20-year-old agreed to rejoin the Championship side last month after making 14 appearances for the club following his loan arrival in January.
Manager Aitor Karanka said: "He is a very important player to us. He's someone I love to have with us because he's a player who came here from Chelsea and his mood was always perfect.
"He was always happy and fighting for his position. He was handed the opportunity to play in the World Cup [for Nigeria] and he is now coming back to us a better player."
Middlesbrough will begin their new season with a home match against Birmingham City on Saturday.
