“Never write this manager off,” said an Aston Villa source earlier in the week.

Villa had been bruised and were now increasingly being doubted. A lifeless defeat against Tottenham Hotspur on Sunday and the criticism that followed — not for the seven changes Unai Emery made but the absence of energy and effort — exacerbated concerns Villa were going to let a third semi-final in as many seasons pass them by.

Multiple observers close to the situation, speaking on the condition of anonymity, felt the manner of defeat against Spurs was a misstep. It cranked up the pressure even further on Thursday’s Europa League semi-final second leg against Nottingham Forest and halted any hope of building momentum. Dressing-room leaders, including Tyrone Mings, spoke publicly, stating the team “lacked desire, passion and energy”. Emiliano Martinez called it the worst performance “by far” this season.

Emery will not admit it but there was a feeling from several sources that his attention was fixed firmly on the Forest game.

He was not being entirely frank in saying the Premier League was still the priority, particularly when the prospect of winning European titles motivates him to such an extent that those close to him believe playing in those competitions is what determines his future. It stokes a different fire inside.

Emery had been plotting his starting line-up for some time. He worked on tweaking Villa’s out-of-possession shape, so they had an extra player in higher areas and could press with more purpose.

Players, meanwhile, were tense, having been fully aware of the scrutiny earlier in the week. Captain John McGinn, who was always going to be fit after resting a tight hamstring against Spurs, started to fire up the dressing room, knowing one goal would shift momentum and the tie would be in their hands. He was nervous, having reaffirmed to team-mates that the time to win was now.

Increasingly, the idea of Victor Lindelof starting in midfield became evident. Lindelof, a central defender, had moonlighted in the position during substitute cameos but never from the outset. With Amadou Onana injured and aiming to return for the final, Boubacar Kamara not fit until the summer, Douglas Luiz out of favour and Lamare Bogarde off colour, Emery and his coaches started to design a blueprint with Lindelof alongside Youri Tielemans.

Team-mates started to note Emery preparing to use Lindelof in midfield. Patterns of play developed, including the Sweden international dropping into right centre-back during deep build-up phases, in turn pushing right-back Matty Cash further upfield and McGinn inside the right half-space. His inclusion was confirmed in a team meeting at the hotel on Thursday afternoon.

The mood of senior figures grew to be one of confidence earlier in the week. When looking towards Forest, one admitted the significance of the game could provoke two responses — “threat or opportunity”.

“I prefer the second one, the energy of opportunities,” they stated.

This was an era-defining match for Emery’s Villa. Director of football operations, Damian Vidagany, called the game “the match of our lives”. Emery intended to create something “that future generations will remember”.

Thousands of Villa supporters and an air filled with claret and blue smoke greeted the team coach as it arrived at the stadium.

Aston Villa’s fans created a raucous atmosphere for the team’s arrival (Michael Steele/Getty Images)

“The energy from the supporters was incredible,” a source close to the dressing room said afterwards.

Ezri Konsa’s pre-match words chimed with the shared sentiment among observers about not conceding early, both because of the two-goal deficit it would create and because it could silence a deafening atmosphere.

Villa’s players and coaches knew they had to harness the crowd, using the emotion of the night without being swept away. In truth, Villa’s best home performances — Manchester City, Arsenal and Paris Saint-Germain — have all come from playing to the gallery, somewhat.

“They (the players) were so, so focused and aware of the momentum,” explained Emery post-match. “We planned before, emotionally, how we were playing the match.”

Removing the passive and sideways nature which has been a problem at times this season, Villa turned Forest around and kicked towards The Holte End in the first half. Their positive ambitions were obvious from kick-off, when Ollie Watkins backheeled the ball to Tielemans before surging forward.

Villa Park was a frenzied tinderbox. Supporters clapped and roared every tackle or pass. The lion on the pre-match tifo behind Emery would have been proud.

Players had to mirror such intensity — in contrast to what they did against Spurs. Watkins sprinted from one end to another, even helping Cash at right-back, while the central defenders and front line squeezed and were aggressive in duels.

Tielemans aimed to make incisive passes into Villa’s three No 10s — Emiliano Buendia, Morgan Rogers and McGinn — and into the feet of Watkins, with Forest defenders backing off.

Villa levelled the tie in the 36th minute through a bandaged Watkins, who had received a cut to the eyebrow from Morato, and Buendia’s jinking feet. Buendia, a player who would have been moved on last summer had Villa received a satisfactory offer, delivered his strongest Villa display, repaying the faith Emery has shown during the campaign.

His second-half penalty put Villa ahead in the tie. Prince William, a keen reader of Villa fan forums, watched on from above and hugged Vidagany in celebration. Rather than the temptation or fear Villa would sleepwalk to another defeat, they were instead suffocating a Forest side who had no answer.

Prince William joined in the celebrations (Carl Recine/Getty Images)

Fittingly, McGinn scored Villa’s third and fourth of the night. He has been the catalyst for the transformation from a mid-table Championship team to Europa League finalists and he often embodies everything good about Villa.

“He sets the standard,” said one Villa source. “He has the total respect of everyone.”

Villa had won 4-0 on the night and 4-1 on aggregate. Under a pressure which raised existential questions about Emery and his team and whether this was it — the final opportunity — the level they reached (“what they had been missing,” said one observer) was extraordinary. 

Others were blown away by what Emery’s side had produced, shocked by the level of dominance. The explanation, however, was the same; Forest, weakened by injuries to key men, could not match the home side’s intensity.

‘Sweet Caroline’ played at full time. Prince William joined in, later going into Emery’s office to offer his congratulations. 

“He was in the dressing room with the players and me and he was so happy,” said Emery.

Players held hands and celebrated in front of the Holte End as Martinez hung from the crossbar. 

“Tonight was up there with one of the best performances I’ve seen from a Villa team for a long time,” added McGinn to TNT Sports.

Villa will head to Istanbul on May 20 with only Freiburg left in their way. At the third time of asking, Emery’s team have progressed from a semi-final to reach a final.

This was a monumental psychological step, now offering the opportunity to win Villa’s first major trophy in three decades and to rubber-stamp the Emery era.