In the most improvised of European Cups, everybody needs to be flexible.
The last eight of the Champions League, shuttled to Lisbon because of the coronavirus emergency and condensed into one-legged quarters and semis, was always going to take clubs out of their comfort zones.
Paris Saint-Germain, preparing in the Algarve for Wednesday’s quarter-final against Atalanta, would, it seems, have been happier in their own high-security training site outside the French capital.
They were perturbed during practice sessions in southern Portugal that passing tourists and potential spies could glimpse what they were doing.
At one point, the PSG staff even instructed their bus driver to move his vehicle a few metres to block off the view of manager Thomas Tuchel’s tactical work.
So it was that PSG found themselves quite literally ‘parking the bus' – to borrow the phrase that usually describes teams who stack men behind the ball when fearful of the attacking might of the opposition.
Any team taking on the fairy tale that is Atalanta would be tempted to park the bus. The Italians have just finished the Serie A season with an astonishing total of 98 league goals, far ahead of the rest.
To reach the last eight of their first Champions League campaign, Atalanta put eight past Valencia over two legs back in February and March.
But for all their breezy, free-flowing football, it is hard to make Atalanta favourites at the Estadio da Luz. As Atalanta's manager, Gianpiero Gasperini, put it yesterday to L'Equipe, "PSG are a team built for the Champions League."
And at what cost. Three years ago, Neymar set the towering record for the highest transfer fee ever paid when PSG stumped up €222m (Dh904m) to trigger his buyout clause at Barcelona.
Or, to put it in the context of this financial mismatch, Neymar cost 11 times as much as Atalanta paid Sevilla last summer to make the Colombian striker Luis Muriel the costliest recruit in their history.
Now compare the operating costs of the Atalanta’s Cinderellas and PSG’s wealthy princes.
Muriel, his colleagues Duvan Zapata and Papu Gomez, might, with bonuses, earn €1.8m in a successful campaign. They are at the top of Atalanta’s salary scale. Neymar, without variables, banks a €36m annual wage.
And yet, in the sealed bubble that is Uefa’s rescue-package for the interrupted Champions League, Atalanta are not the absolute outliers.
A competition that has developed as the domain only of big-city clubs and where the title very seldom ends up somewhere new, looks suddenly, refreshingly open.
In the last-16 Liverpool, Juventus and Real Madrid were all knocked out; Bayern Munich, the favourites, and PSG are the only domestic champions still involved.
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Instead of league title-holders, Lisbon inherits a tub of goals: Atalanta’s 98 in their third-place finish in Serie A; Manchester City’s 102 on their way to second place in the Premier League; Barcelona’s 108 across competitions in a season deemed a failure so far because, although Barca outscored everyone else in La Liga, they finished runners-up.
Unless Bayern or Barcelona, who meet on Friday, go on to lift the trophy, there will be a new name on the big old cup in 2020.
There's a chance it might even go to an unfashionable provincial city, such as Leipzig, or Bergamo, home of Atalanta, population 120,000.
Bergamo would cherish it. The city has had a terrible year, epicentre of Italy’s Covid-19 outbreak, its hospitals and cemeteries were overwhelmed in the spring.
“It was devastating,” said Gasperini. “As a club, we at Atalanta really want to give people who have mourned so much something to smile about.”
The pandemic still defines the circumstances of this unique Champions League, with its vacant grandstands, its abrupt relocation to Lisbon. It puts the event on edge.
Atletico Madrid, who play RB Leipzig on Thursday, have left two players, Angel Correa and Sime Vrsaljko, in Spain because both tested positive for the virus, though they are asymptomatic and, according to Monday's round of tests, have not passed the infection to colleagues.
The health concerns of PSG and Atalanta are everyday ones. Atalanta must do without first-choice goalkeeper Pierluigi Gollini, who has a knee problem.
The French champion’s top scorer, Kylian Mbappe, recovering from twisted ankle, may only be fit enough for the bench while Angel Di Maria is suspended and Marco Verrati ruled out with injury.
Those are significant absentees, but at a PSG who have spent well over €1bn in less than a decade targeting a first Champions League trophy, there should be enough cover.