Aitor Karanka has admitted Jose Mourinho is a different man away from the pressure of elite football.

Middlesbrough's head coach will take on his mentor for the first time on Saturday when the Teessiders arrive at Manchester United looking to end Mourinho's five-game winning streak.

The pair may be at war for 90 minutes as they attempt to get the better of each other, but the friendship they forged at Real Madrid, where Karanka served as the former Chelsea manager's number two for three years, will survive the white heat of battle.

Mourinho's mind games off the pitch and his antics on the sidelines paint a picture of huge intensity, but as a man who knows him better than most, the Boro boss insists there is more to the Portuguese than meets the eye.

Asked if he is different away from football, Karanka said with a smile: "A little bit. Yes, he's different.

"He's different because it is impossible to live 24 hours with that pressure, with that tension that he puts into every single training session or every single game.

"He is different. We are really good friends and we have a really good relationship. But it's football, it's 90 minutes, so for 90 minutes, you can't be friends.

"At the end of the game, we will have a glass of wine, a beer or a Coke and one of us will be happier than the other."

A little more than three years into his first managerial post, Karanka freely acknowledges that he would not be where he is but for Mourinho, and he understandably holds his next opponent in the highest of regards.

Asked what makes the United manager tick, he replied: "It's a mix of everything: his knowledge, his character, his passion, his personality - he has a lot of things.

"The way that he prepares the game is the best; the way that he trains is the best; the way that he is in the changing room is the best, so it's a lot of things and for that reason, he is the best.

"The best example is the relationship he has with the players when he leaves clubs. He has a really good relationship with them all.

"For sure, the players always want to play, but he has a very good relationship with most of the players who have been with him because if he goes to Arsenal, you can see him with (Mesut) Ozil giving him a hug, or when he goes to other places, he has a very good relationship."

Karanka's education under Mourinho has been taken to heart, and no more so that the necessity to be brutally honest with players when the need arises.

The pair forged a close friendship during their time at the Bernabeu (Getty)

The Spaniard said: "I have said a lot of times that to be honest is the best thing. For me, my biggest concern was to do with the players the things that some managers had done with me.

"I had three years with Jose and looking at him treating the players in that way, now I am treating the players in that way, and telling them sometimes things they don't want to hear is the best way."

Karanka has already guided his promoted team to creditable draws at Arsenal and Manchester City, and is working on a plan which may include a surprise for his opposite number.