The Chelsea centre-back was recommended by Mourinho to Karanka, assistant to the self-styled ‘Special One’ at Real Madrid, and he is set to make his debut at Bloomfield Road this afternoon.
He was also the subject of some interest from Hull City, along with Dutch club ADO Den Haag, for whom he made 36 senior appearances on loan last season.
But Mourinho urged him to travel to Teesside to meet Karanka and view Boro’s Rockliffe training facilities at first hand.
He said: “We want to make more signings this month, but it will only be players that I think are better than the ones that are already here. With Kenneth (Omeruo), I think we have this.
“It is important to have those personal contacts. When you have a personal relationship, you know how the other coach works, and that is important.
“Chelsea sent the player here because they think we have the same philosophy.
“Jose knows me as a person and a coach, and for that reason, I think he trusts how we will deal with his player.”
In terms of other recruits, Bradford striker Nahki Wells was under serious consideration, while Blackburn Rovers’ Ruben Rochina has also been linked, possibly as part of a deal that could see Lukas Jutkiewicz heading to Ewood Park. Luciano Becchio is another player linked to the Boro.
Squad reduction is something else Karanka is keen to achieve, with Faris Haroun almost certain to return to Belgium, while the likes of Seb Hines, Luke Williams and Andy Halliday could be farmed out on loan.
“Some players will have to leave. We will have to see what happens as the month goes on, but we are working on players possibly leaving as well as some others signing for the club.
“I have been here two months now and some players who have hardly played. It that is the case, maybe it is better for those players to go on loan so they can play.”