London - Paris Saint-Germain's struggles to avoid an embarrassing group stage exit in the Champions League began when they fell victim to the aura of Anfield and Roberto Firmino's stoppage time winner for Liverpool in September.
But with the roles reversed and the Premier League side headed to the Parc des Princes on Wednesday with PSG needing to win to keep qualification for the last 16 in their own hands, the French champions can take solace in the fact Liverpool pack a far weaker punch on the road in the Champions League.
Anfield has long been credited as the extra man for the five-time European champions, but rarely has the contrast between Liverpool's highs and lows in the Champions League been as stark as in the past few months.
Roma were reeling 5-0 down after just over an hour of last season's semi-final first leg, PSG were outclassed this season despite the narrow margin of the dramatic 3-2 victory and Red Star Belgrade were dismissed serenely 4-0 in October.
Indeed, so easily were the Serbs swept aside that concerns were raised about the growing gulf in resources between European football's elite and once great powers now relegated to also-rans by the geographical lottery that leaves them outside the continent's top five leagues.
Last season Liverpool only secured victory on the road twice in Europe and were left hanging on for a 4-2 defeat in Rome that edged Jurgen Klopp's men through by the odd goal on aggregate. They were then beaten 3-1 by Real Madrid in the final in Kiev.
Two colossal errors by Loris Karius in that final pushed Liverpool to splash out a then world record fee for a goalkeeper in Alisson Becker as part of a £160 million summer spending spree that also brought in Fabinho, Naby Keita and Xherdan Shaqiri.
And while an upturn in fortunes, particularly defensively, has been seen in an unbeaten start to the Premier League season, it has not yet cured Liverpool's travel sickness in the Champions League.
Investment raises expectation
The visitors failed to muster a single shot on target in losing 1-0 to Napoli on match-day two and Red Star enjoyed their biggest night since winning the European Cup in 1991 when the Serbs beat Liverpool 2-0 in their first Champions League victory for 26 years.
"I have only 10 fingers," Klopp quipped when asked to put his finger on what went wrong in Belgrade.
Unless the German finds a way to stop the rot extending to five straight European defeats away from Anfield, Liverpool will likely need to beat Napoli by two goals to progress to the last 16.
That would not be an impossible task. It would rekindle memories of a Steven Gerrard-inspired 3-1 win over Olympiakos with a two-goal margin of victory needed in the final group game of the 2004/05 season - the last time Liverpool won the Champions League.
Yet the investment in the summer to back up a run to last season's final was intended to secure Liverpool's position among the potential Champions League winners, and that means not just relying on the galvanising effect of an Anfield crowd.
"I don't think there is any game in the world where you would say beforehand, 'No chance Liverpool,'" Klopp admitted before his side beat PSG on home soil.
"It is a different club to the club I joined. We got a lot of respect because of the way we played last season."
Klopp has restored Liverpool to their place among the heavyweights of the Champions League.
But with that status comes the demand to land a knockout blow, even against another contender furnished with a near 500-million-euro forward line of Neymar, Kylian Mbappe and Edison Cavani.