Nuno Espírito Santo was in a terrible state, drunk. That, at least, is what his president thought, and exactly what Nuno wanted him to think. A young goalkeeper at Vitória Guimarães, he had been promised that if anyone came in with a $1m offer he could leave, and one day the Spanish club Deportivo La Coruña did just that – only for António Pimenta Machado to renege. “I thought: ‘It’s done, perfect,’” Nuno says. “But I went in and he said: ‘Now it’s five [million].’ I thought: ‘This doesn’t make sense.’” Denied the chance to leave, he considered giving up. Which was when they hatched a plan.

Nuno’s agent messed up his apartment and told Pimenta Machado that the player was in a bad way. “It was an act,” Nuno recalls, pulling faces as he runs through his repertoire that day, 20 years ago, slumping back in his seat, mumbling and unresponsive. “So, the guy came to visit me, the president of Vitória, and my behaviour was … I was acting like I’d come off the streets. And he said: ‘Is he drunk?’ When he left, the president said: ‘Take him tomorrow.’” Nuno pauses then adds: “‘Take him tomorrow … and don’t let them do a test on him!’”

The plan worked; the agent’s name was Jorge Mendes. “Jorge knew exactly what time [Augusto César] Lendoiro, the Depor president, left the club every evening,” Nuno says. “He would leave the office, go downstairs and walk to a restaurant 100 metres away. And Jorge would be there, walking side-by-side. He would drive two-and-a-half hours there from Portugal for 100 metres – but he knew those 100 metres were golden. Then he would drive two-and-a-half hours back to tell me.” Eventually Mendes got the $1m offer; what he didn’t expect was to have to persuade Vitória’s president twice.

In the end, Nuno got the move to Spain. It was the first deal Mendes ever did. Nuno met him when Mendes ran a video shop and a disco; now he is the world’s most powerful football agent. “He deserves it,” Nuno says. “People can’t imagine the hours this guy works. [His reputation] is unfair; they don’t know him.” Mendes’s most famous clients are Cristiano Ronaldo and José Mourinho; his first client is now the manager of Porto. On Tuesday night, he faces Leicester City in the Champions League.

Nuno’s journey began on the island of Sao Tomé, and has already taken in Portugal, Spain, Greece and Russia. Scotland, too: as a coach, that’s where it all started. He is still only 42 and believes that one day it will end in England.

“It’s to do with the global vision I have: we’re so connected, [everything is] so fast now. Why not? The first thing I did everywhere was learn the language,” he says, speaking English with a quiet, almost gentle authority. “I think it also has to do with Portugal and with your family. My grandfather is African, my grandmother is from a small village in Portugal. He arrived on a boat – it was the first time they’d seen a black man. Maybe it starts there; we lived near the Spanish border and my sister and I travelled a lot with our parents.”

Nuno crossed the border in January 1997 to play for Deportivo, before going to Mérida and Osasuna, Dynamo Moscow and Porto. If “playing” is the right word, that is: at Deportivo he made four league appearances in five years. He went to Euro 2008 with Portugal, replacing Quim, but never won a cap. In his first spell at Porto, he won the Uefa Cup and the Champions League with Mourinho, but did so from the bench.

That said, he did replace Vitor Baía late in the Intercontinental Cup final and go on to win on penalties. And he scored a penalty in one game. It was Mourinho’s idea. “It’s strange – I didn’t want it,” he recalls. No? “No. I just put the ball down and kick it so hard. Put it down, three steps and bang! It could go there, there, there …” he says, pointing around the room.” Instead, it went in. “The first thing I did when I scored was hug the other goalkeeper. ‘I’m sorry. For you this is a big humiliation, so I’m sorry.’”

Besides, it all helped, even from there. Nuno watched, listened and learned, ideas forming. He took something from everyone. Emotional management from Mourinho, for example. “Mourinho really changed something,” Nuno says. “He said: ‘We’re going to win’ and we looked at him like: ‘How can this guy be so sure?’ It’s colossal what he did at Porto. When you achieve something like that it is in your memory forever. What I take from him is that belief that he could create something and show us that we were going to succeed, [even] fighting against giants.”

The truism says that goalkeepers don’t make good coaches, so what chance substitute goalkeepers? A good chance, he insists. “You see the game from the best place. All the analyses I do even now [as coach] are from a camera behind the goal. From the side, the perspective is different, you know the exact distances, but it’s not real,” he says, shifting his hands to signal a goalkeeper’s perspective. “But this gives you a real view of the game as players see it. A player never experiences the game from the side.”

“It may not be better but it is my view. I know spaces, distances, and I can judge better the decision-making of the players. I know why this player did not pass to you – because there was an obstacle in front. From the side [you can think]: ‘Why didn’t you pass it …?’ but the lines are different,” he says, laughing as he adds: “I also saw a lot of games from the bench. I watched games, I listened to my coaches, and I talked to my team-mates. ‘Hey, why is he taking off this guy?’”

As a coach, he must know that his players are doing the same to him. “Yeah,” Nuno smiles. “Or the other way round: I can turn to them and say: ‘Shut up, I know what I’m doing, OK?’”

The decision to coach took him to Scotland at the age of 36. He took his coaching badges with the Scottish Football Association.

“They did something I still use,” he recalls. “You know how every meeting starts at the SFA? With a video. The best 50 goals from the 1980s: John Barnes, Ian Rush … and for three or four minutes afterwards everyone is quiet because you get hypnotised. And it was day after day: the best saves, the best one-on-ones, the best shots. I thought: ‘This is brilliant.’

“I went to a meeting: ‘Shhh, do you mind?’ Normally a meeting starts and everyone is talking. This way, it was focused, quiet. And after the video …” Nuno clicks his fingers. “You start and everyone is listening. It’s like opening a window. These guys knew what they were doing. I met so many good people: Jim Fleeting, Donald Park, so many people. They were a big influence on me.”

None more so than Ian Cathro, the young, dynamic Scottish coach who was Nuno’s assistant at Rio Ave, where they were runners up in both Portuguese cups in 2013-14, and at Valencia – where they reached the Champions League places in 2014-15, before Nuno was sacked early in the following season, only for things to get far worse under his replacements, Gary Neville and then Pako Ayestarán.

Nuno has called Cathro a “genius”; now he is assistant to Rafa Benítez at Newcastle. “We will be connected forever,” Nuno says. “We built together. We were young, we started together, we did something nobody believed in. Now Rio Ave are in Europe. If I ever went to the Premier League he would be my first call, the first person I would tell. We have shared so much.”

And Nuno thinks that day will come, too. “[England] is the league that I enjoy most. I love watching the Premier League. One day I am going to coach there, I am sure of it. I love it, I want to be there. If it takes longer, I don’t know. If it takes less, maybe. But one day.” As Nuno talks through his ideas, the influences are clear, the impact of British football. “As a kid, Liverpool was big for us [in Portugal],” he says. “I watched all the Wembley cup finals. [Neville] Southall with the big belly, the goalie: ‘How can this guy stop … I can do that.’ [Bruce] Grobbelaar, too.”

Nuno Espírito Santo during his time in charge at Valencia, with another former Porto coach, André Villas-Boas, in the background during a Champions League game against Zenit St Petersburg. Photograph: Dmitry Lovetsky/AP

There was also something a little “British” about that Valencia side, he agrees: quick, aggressive, pressing high, direct. “All coaches say: ‘We want to control the game, we want the ball, blah, blah, blah, blah,’ but it’s impossible to have the ball all the time,” he says. “If a team is organised it is really difficult to harm them, so you have to search for the moment they are unbalanced. And when is that? When you recover the ball.

“I’m a coach who likes to have the ball but what I really think is: ‘How can you be in charge of the game?’ I think, but maybe I am the only one, that the defensive process can take care of the game. Why is that? Because teams wait to defend. If you create something where you go to defend, to steal the ball where you want, it’s different. A defensive process, yes, but you go for it.

“English football is changing; it’s not this long ball straight up the pitch. There are moments of possession, but the Premier League does allow you a box-to-box game and I enjoy that. Every possession has to have sense [a reason] and that sense has to be to unbalance the other team. English teams don’t have long possession of the ball, but it’s a curious fact: the Premier League has more ball in play than any other league. That tells you that your game has to be more intense, your players have to be more ready, there is more distance for the players to cover.”

The question is obvious: why have Spanish teams done so much better than English ones in Europe? “Difficult,” Nuno says. “I was thinking about that the other day. In terms of the game, I don’t find it [a reason], I really don’t. I don’t see, year by year, why English teams don’t reach a final, with the resources they have. But [last season] you see [Manchester] City in a semi-final. Liverpool in a final. That tells you that it is not like that any more. Premier League teams are ready to [compete].”

Leicester City among them. Nuno knows them well; admires them, too. After he left Valencia last season, England became his main focus of analysis, not least because there was interest in him going there before he joined Porto, the club where he had been twice as a player. As he studied the English clubs, the application of sports science was one of the elements that most struck him. He spent time at Tottenham watching Mauricio Pochettino, while his assistant coach visited Manchester City and Leicester. “You go, you see, you share, you analyse: you see it and think: ‘How can I adapt that? How can this fit my philosophy?’” he says.

“Leicester winning the league was a surprise to everyone but it proved that a united and strong team can achieve big things,” Nuno says. Could it have happened in other leagues? “Honestly, I don’t think so: there are huge differences between the squads of big teams and the others and in long competitions that kind of achievement is very difficult,” he says. “But you can never say never.

“It is going to be a big chance for us to face Leicester, a fantastic challenge, the opportunity to test our limits against the Premier League champions,” he adds. Porto’s limitations are clear, their chances slim. But, then, so were Leicester’s. And, Nuno says: “I have this absurd feeling that I can win every game with any team.”