in Europe's elite club competition back in the 2003-04 season when they thrashed AC Milan 4-0 in their quarter-final second leg in La Coruna to shock the reigning continental champions and progress to the last four 5-4 on aggregate.
Uruguayan forward Walter Pandiani scored the opening goal in the fifth minute at the Riazor on that memorable April night, when the Galician club stunned a Milan side featuring Paolo Maldini, Kaka and Andriy Shevchenko.
Now 37 and playing in the Spanish third tier for Majorca-based Atletico Baleares, Pandiani believes Barca will also need an early goal if they are to have any chance of reaching next month's final at London's Wembley stadium.
"Scoring so early in the match was key for the team to gain confidence," Pandiani, whose goal-scoring prowess earned him the nickname "The Rifle", said on UEFA's website (www.uefa.com).
"If you don't manage to score in the first half, as soon as possible, then you start to rush things," he added.
"That early goal gave us the peace of mind to continue playing well."
Barca's chances of keeping alive their bid for a third European crown in five years may appear remote, especially as they failed to score in Munich, but Pandiani said Depor were in a similar situation in 2004.
"Even if we were achieving important things in the Champions League nobody believed in us, especially because it was Milan we were up against," he said.
"But we believed in ourselves and our fans were also there to spur us on.
"The excitement in the dressing-room at halftime showed that it would be difficult for them to do us damage that night if we continued with the same mentality."
On the evidence of Saturday's 2-2 La Liga draw at Athletic Bilbao, Barca's hopes on Wednesday will again rest on the shoulders of their World Player of the Year Lionel Messi.
Messi, who is coming back from a hamstring strain, was initially rested in Bilbao and Barca found their cutting edge only when he replaced midfielder Xavi on the hour before scoring once and setting up Alexis Sanchez.
He appeared short on fitness and was well shackled by the Bayern players in Munich last week and even the talismanic Argentine may not be able to rescue Barca's Champions League campaign this time.
They already had to come from behind to get past AC Milan in the last 16 when they lost 2-0 in Italy before Messi inspired them to a rousing 4-0 victory at the Nou Camp.
Only three clubs have overturned a four-goal first-leg deficit in UEFA competition and Bayern coach Jupp Heynckes was on the losing side on one of those occasions.
He was in charge of the Borussia Moenchengladbach side that beat Real Madrid 5-1 at home in the 1985-86 UEFA Cup third round only to lose the return game 4-0.
"It was the worst moment of my career. I no longer wanted to be a football coach," Heynckes said on UEFA.com. "It was worse than the death threats I received later in my career."
Elimination for Barca would leave La Liga as their only chance of silverware this season and, with an 11-point lead over current champions Real Madrid with five games left, they are close to a fourth title in five seasons.
However, a domestic league crown would be scant consolation for a team who have set a new standard for European clubs in recent seasons and won the Champions League in 2009 and 2011.
Heynckes has said he will not be instructing his team to play a cautious game on Wednesday despite a string of players risking suspension for the final with another booking.
"I will nominate my best possible team," he said after Bayern, already installed as German champions, set a Bundesliga record of 84 for the most points in a season with a 1-0 victory over Freiburg on Saturday.
"My players will have to be disciplined and that means no gestures, no unnecessary fouls and no falling for any provocation. That will be decisive."
Six players, including captain Philipp Lahm, central defender Dante and playmaker Bastian Schweinsteiger, will miss the final if they pick up another yellow card.
"I want the same attitude, commitment and tactical play (as in the first leg)," said Heynckes, who will make way for former Barca coach Pep Guardiola at the end of the season.
"They are still the best team in the world. We know they have had great results and comebacks at home. Their pride has been wounded and they will try everything."
Barcelona: 1-Victor Valdes; 2-Daniel Alves, 3-Gerard Pique, 15-Marc Bartra, 21-Adriano; 6-Xavi, 16-Sergio Busquets, 8-Andres Iniesta; 17-Pedro, 10-Lionel Messi, 7-David Villa
Bayern Munich: 1-Manuel Neuer; 21-Philipp Lahm, 17-Jerome Boateng, 4-Dante, 27-David Alaba; 31-Bastian Schweinsteiger, 8-Javi Martinez; 10-Arjen Robben, 25-Thomas Mueller, 7-Franck Ribery; 9-Mario Mandzukic
Referee: Damir Skomina (Slovenia)