Aitor Karanka finds watching Manchester United a strangely familiar experience. When he analyses their shape, structure and default tactical responses, the Spaniard sees distinct shades of his own Middlesbrough side.

Sometimes, as he sits in front of his TV screen studying United’s play, Karanka second-guesses José Mourinho’s substitutions or formational tweaks but this impressive knack should come as no surprise. Quite apart from having spent three years as the former Chelsea manager’s assistant at Real Madrid, he readily acknowledges the pair are soulmates in philosophy. This bond, something personal and professional, makes the prospect of their crossing managerial swords for the first time on Saturday at Old Trafford particularly intriguing.

“In terms of tactics, we’re similar to United,” Boro’s manager said. “They play with the same shape, they’re confident with the transitions. They have a reference player up front in Zlatan Ibrahimovic, albeit with different skills from our reference player, Álvaro Negredo.”

Karanka believes some of the similarities stem from the fact that he and Mourinho are control freaks. “My thinking was more or less the same before I met José because I, too, like to have everything organised in my life,” he said. “You want your team organised, so now when I analyse Manchester United, when they don’t have the ball it’s easy to compare them with us – but the better players you have the better you can play.”

The pair did not know each other before joining forces at Real Madrid. “We didn’t have a relationship,” said Karanka, a former Real centre-half and Spain Under-16 coach. “The only times I’d come across him was once when he was working at Barcelona and the second time when he was the coach at Porto and he said in a press conference that I should have been sent off.

“Then, [Real’s] Fernando Hierro called me to say José wanted to speak to me and José called; that was our first conversation but everything he promised me in that conversation happened in our three years together. He told me he didn’t want an assistant who always says ‘yes’. He wanted an assistant who gives him his point of view. The main thing you can say about José is that’s he’s honest; everything he said in that conversation was 100% true – although he did say he’d send me to face the press a few times and he actually sent me 89 times. José taught me the importance of honesty with players, even when you tell them something they don’t want to hear.”

Karanka had been recommended by three former Real team-mates. “Luís Figo, Clarence Seedorf and Predrag Mijatovic,” he recalled, smiling slightly before explaining that by their third year together Mourinho delegated the vast bulk of coaching duties to him.

This hands-off stance possibly helped him retain a certain mystique, although Karanka stressed the Portuguese coach watched the majority of the training sessions, reading the play with the sort of forensic insight that has become his hallmark, and is the basis for one of the Boro manager’s favourite Mourinho anecdotes.

“When we played against Manchester United in the Champions League José told me to change Benzema – for I don’t remember what player – but when I called Karim, Nani was sent off,” Karanka said. “Two seconds later, José looked at me and said: ‘No Karim, Luka Modric instead’ – and Luka Modric was the player who changed the game and won it for us. José didn’t need one minute to think about things, he just had two seconds but the moment he saw the red card, he saw the solution and changed his ideas on the pitch. When it comes to watching the game I don’t know how many steps forward he is from the rest.”

Not that a man who is no slouch when it comes to his own analysis regards his old boss – whose United players are on a five-game winning run – as quite invincible. “My ambition is to beat José on Saturday,” he said. “I hope, one day, I can manage in the Champions League and do something like him but I’m doing the steps at the moment.”

Although similarly intense to Mourinho, Karanka is much less overtly confrontational. While demanding, he refrains from indulging in the mind games that represent another of his mentor’s trademarks and seems altogether more down to earth and infinitely less self-centred.

In private, though, Boro’s manager sees an alternative and appealing Special One. “José’s different, well a little bit different, because it’s impossible to live for 24 hours with that pressure, that tension he puts into every single training session or game,” he said. “We’re really good friends but for 90 minutes on Saturday, we can’t be friends. I’ll try to surprise him – but it’s difficult to surprise José; he’s the best.”