In a galaxy far, far away, a La Liga football club proved that one can overturn a damaging first leg lost with a 4-0 win in the return fixture.
That was Deportivo de la Coruna in 2004 against the then-reigning Champions League holders AC Milan.
But unlike the challenge facing Barcelona on Wednesday night at the Nou Camp, Deportivo at least had an away goal to give them hope, having lost their first leg 4-1 in Italy.
Barcelona's humiliation three weeks ago instead leaves them looking to haul back a 4-0 deficit against a Paris Saint-Germain side who aren't the type of side to lose by that margin regardless of the opposition.
Even if Barcelona are to score four goals tonight - never impossible when you have Lionel Messi, Neymar and Luis Suarez up front - they would need to keep a clean sheet to give themselves any hope. And given that Barca are not exactly watertight defensively and PSG have weapons like Edinson Cavani, Angel Di Maria and Lucas Moura to deploy, the odds are now stacked heavily in PSG's favour.
Barca of course have had the occasional habit of finding themselves chasing after a poor first leg. In 2009-10, Pep Guardiola's side went down 3-1 away at Jose Mourinho's Inter during the peak tiki taka years.
A defensive from Inter managed to prevent Barca reaching that year's final. In the 2012-13 season, Barca fell to a surprise 2-0 defeat at AC Milan in the first leg of a last-16 tie.
But the second leg saw them roar back in style with a 2-0 win that saw Lionel Messi scored twice to put Barcelona back on terms - the first crucially coming on five minutes.
That was no vintage Milan side though and this current PSG side can lay claim to being a stronger outfit.
Borussia Dortmund players (l to r) Marcel Schmelzer, Pierre-Emerick Aubameyang, Marc Bartra and Nuri Sahin stretch on the training grounds in Dortmund, Germany, 7 March 2017. BVB will meet Benfica Lissabon in the second round second legs of the Champions League (8.03.). Photo: Bernd Thissen/dpa
Elsewhere, Borussia Dortmund welcome Benfica to Germany, looking to overturn a 1-0 first leg deficit.
Dortmund had a host of chances to get at least an away goal two weeks ago but failed to deliver.
However, they tuned up at the weekend with a 6-2 destruction of a soon-to-be managerless Bayer Leverkusen side with Pierre-Emerick Aubameyang returning to form with a brace. However, they did lose Marco Reus to injury.
Benfica, of course, have strong European pedigree from the 1960s, and they did reach the quarter finals of the Champions League last season.
They will probably need to keep a clean sheet tonight to have any chance of progression however as Dortmund have major strengths in attack.
And in a weak group, Benfica only kept two clean sheets in home and leg games against Dinamo Kyiv, conceding a full 10 goals in total including a 4-2 loss at Napoli and a 3-3 draw at Besiktas.
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