Ander Herrera puffs out his cheeks for the hundredth time, eyes gleaming again, and says something that does not need saying: “I like football.” You can tell. You can tell by the way he talks – and talks and talks – by the enthusiasm and the explanations, analysis not just an answer; by the way he reels off lists and lineups and how, when asked if he remembers matches, moments, he does not say “yes” but “yesyesyesyesyes”; by the way one actually believes him when he says he knows what it means to play for Manchester United; by the way he talks about Northampton away and wishing he could watch United with the fans, only to correct himself and say that, actually no, that would mean he was not playing.

Herrera says when he stops playing football he will watch football; he talks about old grounds, everyone standing, adopting an English phrase with Spanish currency, a mark of nostalgia and authenticity: “I’m a bit ‘Against Modern Football’”; and admits to being “football mad”. But it is a redundant confession, already clear in the admiration – the reverence, even – with which he talks about players, places and matches.

The next match especially, is one that feels fitting, for Spain against his United captain, Wayne Rooney. Framed portraits cover this room, the room next door and the corridor outside: every Spain international from Abel Resino to Andoni Zubizarreta. Soon Herrera will join them. Tuesday is his debut – at the place he calls “a legendary stadium with an incredible history”. It is his kind of place.

Maybe it has been worth the wait, after all. Herrera is 27. A European Under-21 champion who is almost a decade into his career; it has been so long coming Rooney kept joking that the first time he ran out as an international would indeed be at Wembley – but not in red, in white. “Whenever Spain did not call me, Wayne would say: ‘Good: wait, you’ll end up playing for us,’” Herrera says, adding, just in case: “He was joking, eh. He knew my dream was always to play for Spain.

“I know Vicente Del Bosque wanted to call me a couple of times. One time I broke a rib playing West Ham, jumping with [James] Collins, and the chance slipped by. That was hard. I’ve always had faith, but you’re aware that Spain has the best midfield in the world by a long way. Better than Argentina, Brazil, anyone: Iniesta, Silva, Cazorla, Mata, Koke, Isco, Tiago. Enough to pick three midfields, all of the highest level.”

Paul Scholes once described Herrera as United’s best signing – “For a legend like him to say that is amazing,” the Spaniard says – but there was no place in the national squad until now. The arrival of Julen Lopetegui helped; so did the arrival of José Mourinho, changing his position. That list is no longer a list of Herrera’s direct competitors. “I’m here because Mourinho’s given me the chance to take a new role,” he says. “It’s more defensive: hold my position, don’t lose the ball, win it, bring it out fluidly, that ‘rest defence’. I’m enjoying it. I’m there for others.”

Paul Pogba, for a start. “Paul’s an offensive player; he needs freedom and the team needs him to have that,” says Herrera. “He can score 10 a season. With his strength, the way he hits the ball with both feet, his ability in the air, you have to make the most of that.”

Herrera did not appear the typical Mourinho player, and the same was even more true of his best friend at United, Juan Mata. The assumption was they would never suit him, Mourinho’s arrival a prelude to their departure. He was too defensive, too preoccupied with physical presence, too committed to the counterattack, not bothered about the ball. They were the opposite. Herrera once said that one thing he liked about Louis van Gaal was that he placed mucha, mucha, mucha importance on possession. Mourinho does not. The end was nigh. Yet here they are.

“That’s a myth,” Herrera says. “There’s an idea of Mourinho that’s flawed. In many games we’ve had more possession. Liverpool had more but otherwise we’ve had more of the ball and more chances. Liverpool have been scoring loads: to limit them to two shots, both from distance, is a success. And with Ibra’s chance we could have won 1-0. To go to Anfield, the form they’re in, and stop them deserves praise. Some games you have to shut the door because they’re ‘on fire’. Other days like Burnley, Stoke, Swansea, it’s you who has to attack.

“Even against Chelsea possession was ours until the last 10, 15 minutes. OK, we deserved to lose but not 4-0. We had chances for 4-2 or 4-3. Mourinho’s an attacking coach; what he’s not is a kamikaze: he doesn’t have us playing like mad men. He likes the ‘rest defence’ but he’s an attacking coach who gives players freedom. He’s also honest, sincere, says what he thinks to your face. If a coach isn’t honest, players rumble him. There’s a very good relationship. Mourinho’s very straight.”

Unlike Van Gaal? “It’s ungentlemanly to talk about coaches who’ve left. I’m grateful to Van Gaal: he brought me to United and I played 71 games so I wouldn’t say a bad word. I prefer to talk about the present. The team’s fine, enjoying the work, training well. I like Mourinho’s sessions: very dynamic, always with the ball. There are no really long sessions or talks. He understands what a footballer needs: twenty minutes, that’s it. No time to lose concentration. We’re still there, and we should have five points more. We deserved to beat Stoke and Burnley. That was unbelievable. 37 shots, they have one and ...”

Herrera blows out his cheeks again. “Incredible, incredible. I spoke to Juan [Mata] and we’d never known anything like it. That happens once a season, but it’s already happened twice. The ball hits the post and goes wide; soon it will hit the post and go in.”

Herrera is as effusive about team‑mates. Is Zlatan Ibrahimovic quite so, well, ‘Zlatan’ as he seems? “He’s ... curioso”. Herrera replies. There is a pause. “He’s a superstar, but he’s joking all day, winding people up, and he accepts you doing it back. He’s 35 and look at him,” Herrera continues, raising a skinny little finger. “Like a lad of 28. He looks after himself, eats well, stretches, does his recovery work. There are no miracles – if you’re like that at 35, that agile, that good, it’s because you’re professional. You give Ibra a melon and he turns it into a ball.”

Other team-mates will be opponents on Tuesday. Jesse Lingard “understands the game very well” and, as for Marcus Rashford, Herrera laughs. “We wind him up: ‘How much money are you going to make?!’ Because he has everything: he’s quick, shoots well with both feet and I most like his willingness to defend. But, look, he’s 19: we can’t ask him to score 40 goals. Be patient. There will bad times but there will be good too because he’s so talented. A humble kid with a brilliant future.”

Then there is the man Herrera seeks out most, the man trying to sign him for England. “I talk to Wayne a lot,” he says. Herrera uses the word sabiduría to describe the forward. It means ‘wisdom’, which may appear a strange choice but he means it: the admiration and affection are genuine. “He’s as futbolero [football-mad] as I am. He has so many stories. I love talking to him because he knows the game so well.”

When it is suggested that Rashford and Rooney are at opposite ends both for United and England, one arriving on stage, the other leaving, Herrera responds swiftly. “Well, ‘leaving’? Let’s see. Look, Wayne’s been playing at the highest level from 16. I didn’t reach the first division until I was 20; he’s got four years on me. All that adds up. Sunday, Wednesday, Sunday, Wednesday, national team, Euros, World Cup, competing, winning, again and again. Fifteen years at England’s biggest club has an impact; people need to understand that. And he never disconnects, even when he’s not playing. He’s there, talking about how we can improve.

“His attitude’s impressed me. Wayne’s a few goals from Bobby Charlton, yet we get two penalties and he gives the ball to Paul [Pogba] and Anthony [Martial] because they need the confidence. That shows you the class of person he is. The day I leave football, I’ll remember that. And last season he pulled our chestnuts out the fire loads of times.” Herrera laughs. “Is there an English phrase for that?” he asks. “Anyway, he’ll still do that: against Swansea he was fantastic.”

Herrera and Rooney have talked England, too. “I don’t think [fatigue] is a convincing argument. It’s true there’s an extra cup in England which has an impact but I think you notice that more in Europe than with the national team. It’s also true that games are madder – I run more than I did in Spain – but I don’t think it’s harder physically. The intensity’s high but not much higher than Spain. I don’t think you pay for that.

“There’s a lot of pressure. I know, I see it: the media’s hard, very hard. They’re tough with the national team. As soon as something goes wrong, the players take some terrible hits. And I think there’s a kind of disencanto [roughly, “a disenchantment”] with the national team now, isn’t there? Games where Wembley hasn’t filled. But they have the foundations, reason to believe and phenomenal players.”

This time Wembley will fill. Herrera will be there – and not in the crowd. His family will be, though. They travelled to Granada in case and from there to London. He is so enthusiastic about England that it feels fitting for him to have waited to make his international debut there and, besides, what is three more days? “I knew sooner or later the chance would come. I worked for this: every day as if it was the last.” In the end he got there: the same place where he won his one senior medal (last season’s FA Cup), if not the same dressing room. “Up the corridor to the right,” he says. “But I don’t know if that’s England’s or ours.”

As Rooney always said, he will be there too, but wearing a different shirt. And Herrera will not be swapping, not this time, not ever. “If I play, the shirt is for keeping,” he says. “Although if Wayne doesn’t mind giving me his and not getting mine, great. That would be a nice memento. Maybe I’ll tell him that.”