Karanka left Real Madrid in the summer on the arrival of Carlo Ancelloti, who took over from Chelsea-bound Mourinho. Before joining their coaching staff, he was manager of the Spanish U-16 team.
He also represented Real Madrid as a player, making 93 appearances for them between 1997 and 2002 and winning the Champions League with them in 2000 when they beat Valencia 3-0.
The Vitoria-born defender started with Athletic Bilbao and returned for a second spell with the Basque club after leaving Madrid before finishing his career in the USA with Colorado Rapids.
Karanka won a single cap for the Spanish senior team, having played 14 times for their U-21 side.
He also represented Spain in the 1996 Olympic football tournament, where they reached the quarter-finals, and also played for the Basque country team.
In his first season in charge at The Riverside he led Middlesbrough to a 12th place finish in the Sky Bet Championship. In 2014/15 season Karanka led Middlesbrough to the Championship play off final.
Source: Middlesbrough FC