Valencia's scattered defenders looked like a collection of punch-drunk strangers after Atalanta wing-back Hans Hateboer tore gleefully down their vacant left flank and smashed home his second goal of the match.
With just over an hour played, Gian Piero Gasperini's blue and black wrecking machine were 4-0 up in the club's first ever Champions League knockout tie.
Blistering long-range strikes from Josip Ilicic and Remo Freuler sparked scenes of delirium in the stands at San Siro - Milan's celebrated football coliseum and temporary home to Atalanta's European home matches, with more than 40,000 fans making the pilgrimage from Bergamo for the most significant night in their club's 112-year history.
The other standout victory in the last-16 of Europe's top competition, of those ties completed, came via very different means. There is something irresistibly Machiavellian about Diego Simeone's iron-willed Atletico Madrid teams when they are pushing all the right buttons at just the wrong time as far as illustrious opponents, such as reigning champions Liverpool, are concerned.
Simeone yelping with outstretched arms as he cavorted towards the Anfield Road End after Alvaro Morata's tie-sealing goal was an image ripe for any best of Champions League compilation. Only now it is burned onto our collective consciousness with an underlying unease.
A day before Atleti's Merseyside heist, Atlanta continued their artful disembowelment of Valencia, winning 4-3 at the Mestalla to seal a remarkable 8-4 aggregate triumph. Only there were no fans present to witness Ilicic's four-goal masterclass. Coronavirus had its grip on the continent and pulling down the shutters on football would soon tumble down most people's list of priorities.
"Bergamo, this is for you. Never give up," read the slogan on a t-shirt the Atalanta players held up to a television camera after their eerie victory in Spain. Their home city was already dealing with a mounting death toll.
Professor Fabiano Di Marco, head of pulmonology at Bergamo's Pope John XXIII Hospital told Corriere della Sera the initial match at San Siro, with all of its accompanying travel and social interaction had been a "biological bomb" – a description with which mayor Giorgio Gori concurred.
“It was not the right decision to stage the match," Liverpool City Council's newly installed director of public health Matthew Ashton said of the Atletico game, where 3,000 travelling supporters attended against the backdrop of an increasingly grave situation in Madrid. "People don’t make bad decisions on purpose – perhaps the seriousness of the situation wasn’t being understood across government at that time."
Atalanta are Bergamo and Bergamo is Atalanta – you can't have one without the other.
Atalanta's transformation into Europe's great entertainers is every bit as unlikely as it is glorious.
"All the stereotypes of Italian football being 0-0, 0-0, 0-0 – that's Edy Reja's dream. He doesn't ever want a goal to be scored in a football match," said Conor Clancy, editor-in-chief at the Forza Italian Football website, when discussing Gasperini's immediate predecessor.
"It was some of the most turgid football I have ever seen in my life, the last season before Gasperini came in. So when he came along you wondered how it was going to work – a team of cloggers who probably can't pass the ball five yards and Papu Gomez being the only footballer in the group.
"But he just improved everybody. I don’t really know how he's done it."
Progress since under a coach who was best known for a swiftly aborted five-game spell in charge of Inter in 2011 has been staggering.
Atalanta's best points total in Serie A was 52 upon Gasperini's arrival. In 2016-17, they amassed 72 and have never been below their previous best. They have finished fourth, seventh and third in his completed campaigns, fired by a freewheeling attack in which the talismanic Gomez and mercurial Ilicic have a prolific ally in Duvan Zapata.
Last term they were Serie A's top scorers with 77 goals and already have 70 after 25 matches in 2019-20 – the reward for an audacious and bold tactical setup, where industrious central midfield duo Freuler and Marten de Roon operate in front of a ball-playing back three, while interchanging with a pair of adventurous wing-backs and a creative forward trident.
When everything clicks, opponents are utterly overwhelmed. In between the Valencia matches, Atalanta scored seven times in a Serie A match for the third time this season when they hammered Lecce 7-2. Either side of the mid-season break, Milan and Parma were each dispatched 5-0. Zapata, Ilicic and Luis Muriel are all into double figures for the league season.
They are an easy side to adore for a fervent fanbase. Gasperini has expressed an ambition to be seen as Atalanta's Alex Ferguson and has, along with Gomez, been granted the freedom of Bergamo.
"Papu is the symbol of this club and an environment made of many carefully selected players," the club's former defender Guglielmo Stendardo told Stats Perform at the end of last month.
"He is the symbol of Atalanta and I hope he can go on like this for many seasons. He is still super fit, he performs having fun. This is the spirit of the complete sportsman.
"Players like Zapata, Ilicic and Gomez show Atalanta is an arrival point for footballers, whereas before it was more of a springboard for young talents. Now this is a club consistently top ranking in Italy and in Europe."
Club president Antonio Percassi appeared equal parts bemused and delighted when he was able to rebuff Inter's €50million approach for Zapata last year. It was a sign his squad drawn from a vast global scouting operation, pulling would-be stars and misfits from Argentina, Netherlands, Switzerland, Ukraine and beyond, are now dining at the top table.
For all this emphatic progress, the showdown with Valencia – reached despite losing their opening three Champions League group games before drawing the fourth against Manchester City, who finished with Kyle Walker in goal at San Siro – came with the enticing promise of being able to display the Gasperini project, in all its glory, to the world.
"The whole city shut down for that game," said Clancy, who also counts himself as an ardent Atalanta supporter. "There was a driving school, which was closed for the day because the owners went down to Milan for the match.
"Just a lot of little things where people were putting signs up all over the city saying we're closed for today because it's a huge day in the history of the city, the football club, the people, everything.
"That set the scene before the game even kicked off. After that game, I'm in a few Atalanta forums and Facebook pages, and I've never seen anything like it. The emotion was just phenomenal. Being at San Siro as well was pretty special.
"That connection has always been there. Atalanta are Bergamo and Bergamo is Atalanta – you can't have one without the other.
"If you go to any city in Italy and ask people what they're doing on Sunday, they'll say 'I'm going to the stadium'. In Bergamo they say 'I'm going to Atalanta'. There's no mention of a sport, no mention of a place. It's just Atalanta."
Cholo is a leader, a fighter, the emblem and the mirror of what Atleti itself is.
Undiluted passion, common purpose between players and supporters and an unflinching commitment to a tactical idea are traits Atalanta hold in common with Atletico, even if the realisation on the field could scarcely be more different.
A Copa del Rey and LaLiga winner during his playing days at the Vicente Calderon, Simeone returned in 2011 to take charge of a club with a reputation for burning through head coaches. He promptly won the Europa League and then set about pestering Spanish football's duopoly.
Champions League final losses to Real Madrid in 2014 and 2016 stung horribly, but steering a course to LaLiga glory in 2013-14 remains a crowning achievement for one of this era's giants of the dugout.
"Regarding what Cholo means to us, the supporters, it is everything," said Atletico fan Oscar Medina Ochoa, who made the trip to Anfield. "He is a leader, a fighter, the emblem and the mirror of what Atleti itself is.
"A motto of the club, the lyrics of our anthem, is "'courage and heart'. That is what he represents, from his time as a player and now as a coach.
"His way of understanding the club and teaching values has made many people believe a [certain] way. It is true that there are people who no longer follow his philosophy and the press criticise him for the tactics, the financial outlay... but the truth is that since he has been there, the team has an identity of yesteryear - of a winning team."
Jurgen Klopp unequivocally added his name to that list of non-believers after his Anfield ordeal.
Atletico soaked up waves of pressure with something approaching masochistic delight, before springing from their shackles to score three times in extra time for a 3-2 win on the night and a 4-2 aggregate triumph.
The first of Marcos Llorente's crisply struck brace was timed for maximum torment, coming within three minutes of Roberto Firmino giving Liverpool the lead in the tie for the first and only time.
"I am completely happy with the performance. It's so difficult to play a side like this," Klopp told BT Sport.
"I don't understand with the quality they have the football they play. They could play proper football but they stand deep and have counter-attacks.
"We accept it, of course, but it doesn't feel right tonight. I realise I am a really bad loser, especially when the boys put such an effort in against world-class players on the other side who defend with two rows of four."
Atletico right-back Kieran Trippier told the same UK broadcaster that Simeone reprises his histrionic touchline persona in training every day – a frankly startling prospect.
"I’ve been here seven months and I’ve never seen anything like it, to be honest," the England international said.
"Starting from Diego Simeone – everyone feeds off him – he's an unbelievable manager. I can’t really explain how good it is here, it is just an unbelievable feeling and I’m proud to be part of this team."
The work ethic in which Trippier and others delight aligns Atletico with the club's traditionally working-class roots and Simeone has made this quality a non-negotiable when it comes to frequently bloodying the noses of Europe's aristocrats.
This week, the Champions League quarter-finals were due to commence and there would have been no more compelling tie than Atalanta versus Atletico Madrid.
How would Simeone, whose team have scored a paltry 31 times during an uneven LaLiga campaign, plot a path to outgun Gasperini's trigger-happy mavericks? How would the free-spirited Italian entertainers avoid succumbing to what former Australia cricket captain Steve Waugh (a man very much cut from the same sporting cloth as Simeone) termed "mental disintegration"?
And yet, two sets of players and fanatical fanbases in thrall to two radically different footballing visions must instead reckon with a reality where there is no comfort in hypotheticals.
If they had known the consequences, it is clear that everything would have been cancelled
"It is true that no-one prohibited the visit, there were simply the recommendations of the club," said Medina Ochoa, who spent the afternoon before Liverpool v Atletico at the city's famous Cavern Club, where fans draped an Atleti scarf over the statue of John Lennon on Matthew Street.
"If they had known the consequences, it is clear that everything would have been cancelled."
That March midweek developed queasily, with a sense that events were moving a step faster than any response.
On the day of the Liverpool-Atleti game, the Spanish government issued revised guidance to declare non-essential travel outside Madrid to be "irresponsible", while visiting fans were already in or en route to the UK.
Liverpool were given the go-ahead to allow fans in. Premier League games were scheduled that weekend. Then, on the Thursday, Arsenal head coach Mikel Arteta tested positive for COVID-19. England's top flight joined the vast majority of elite European leagues in being postponed that weekend. None have returned due to tightening lockdown measures and a climate of unprecedented uncertainty.
As of April 4, Bergamo had 2,245 declared deaths. An investigation by local newspaper Eco di Bergamo estimated the virus killed around 4,500 in March. Lombardy, which includes Bergamo, has confirmed 9,722 deaths and 15,147 recoveries form 53,414 cases, making it the most affected region in Italy.
The Community of Madrid counts 5,800 deaths from 43,877 cases, with 21,121 sufferers recovered. Unfortunately, Atleti great Jose Luis Capon, former title-winning boss Raddy Antic and youth team player Christian Minchola will not be counted among the latter number.
"In this very moment of worldwide emergency, we all have to feel a bit Bergamaschi," Stendardo said.
"I have lived for five and a half years in a fantastic town like Bergamo, I realise how hard it is to fight back against the problems this virus has created.
"I am so devastated right now as I know Bergamo's citizens are rooted in their territory, have a strong sense of duty and incomparable work ethics. They don't deserve all this."
The work ethic Stendardo alluded to is evident among Atalanta's ultras, whose community spirit has been a visible part of the response.
Starting with a plea for fans to stay home after the Valencia triumph – traditionally any significant Atalanta win on the road is followed by fans greeting them with banners, flares and songs upon their return – the Curva Nord group donated a combined €40,000 that would have been spent on travelling to Spain to local hospitals.
A further €10,000 has been donated via a PayPal appeal since, while Curva Nord members also documented their efforts volunteering to build a temporary hospital in Bergamo.
While Ilicic has donated his hat-trick ball from the Mestalla to the Pope John XXIII Hospital, Atletico players have also been playing a part in Madrid – most notably in accepting 70 per cent pay cuts to ensure non-playing staff receive their full wages during the crisis.
Members of Simeone's squad have been conducting video calls with fans young and old, with Koke's conversation with the club's socio number one Pedro Palermo particularly touching.
All of these acts, big and small, show two clubs woven through the fabric of their frayed communities, becalmed but promising better days.
Italy marked one month in lockdown this week, a moment when in a parallel existence we would have been pouring over the fallout from an Atletico v Atalanta first leg and building up to next week's intriguing second instalment.
For now football belongs in the background, sustained in the hopes, dreams and memories of fans in Madrid, Bergamo and beyond. It feels like a comfortably fitting waiting spot for two inspirational teams.