After performances ranging from inconclusive to dismal in their opening games, Manchester United, Manchester City and Inter Milan must step up a gear in their second Champions League outings on Tuesday.
Although the trio will be fully aware that no club has retained the trophy since the league format was introduced 20 seasons ago, most observers agree it will take a Herculean effort to wrest the cup from Barcelona.
Dethroning the Catalan club will certainly demand an improvement on United's opening draw at Benfica, City's stalemate at home to Napoli on their Champions League debut and Inter's shock home defeat by Turkey's Trabzonspor.
City, joint-top of the Premier League with United, suffered from nerves in their opener against Napoli, who held them 1-1 at the Etihad Stadium to leave manager Roberto Mancini admitting his expensively assembled side had been "nervous because it was the first game".
But he predicts that the pressure has now subsided as City -- for whom Carlos Tevez could feature with weekend goal hero Mario Balotelli suspended -- head off to their first away encounter in Group A.
The sides have never met before but Bayern have the edge in experience, even if City can boast four former winners in their squad in Tevez, Balotelli, Owen Hargreaves and Yaya Toure.
Bayern have already laid down a marker by winning 2-0 away to Villarreal and a win on Tuesday would almost give them a foot in the next stage.
Bavarian confidence is sky-high after a weekend drubbing of Bayer Leverkusen moved them two points clear in the Bundesliga.
"We've a massive game ahead of us and we'll have to be at the top of our game for the whole 90 minutes," says Bayern coach Jupp Heynckes, whose club have racked up eight straight wins and can point to just one home loss ever to English opposition -- a 1993 UEFA Cup reverse to Norwich.
Midfielder Bastian Schweinsteiger said the whole side was looking forward to the clash but warned "this is probably our toughest match of the season so far, a real challenge".
Napoli will bid to stay in the mix by inflicting more woe on Villarreal, who knocked the Italians out of last season's Europa League.
Manchester United, meanwhile, have to tackle Swiss side Basel without the services of hamstring victim Wayne Rooney.
Manager Sir Alex Ferguson is pondering his most effective line-up in Rooney's absence, while awaiting news of the extent of the injury Javier Hernandez suffered in Saturday's 1-1 draw at Stoke, which ended United's perfect start to the league season.
"I do need to get all the squad moving. I think there will be changes on Tuesday," Sir Alex told manutd.com.
"If we win our next three games, we can utilise the squad... Although I want to make changes, I don't want an embarrassment. So changes have got to be made with a mind of still winning the game."
Basel's coach Thorsten Fink has a special reason to want to put one over United, as he was in the Bayern Munich side that lost the dramatic 1999 final to the Red Devils in Barcelona.
Inter will hope their nightmare start to the campaign is over after sacking Gian Piero Gasperini and bringing in former Chelsea and Juventus boss Claudio Ranieri.
Ranieri got off to a winning start with a 3-1 victory at Bologna on Saturday, but playmaker Wesley Sneijder, Brazil full-back Maicon and Serbian midfielder Dejan Stankovic will miss the Group B meeting with CSKA in Moscow.
In the same group, French champions Lille visit Trabzonspor, having thrown away a 2-0 lead to draw 2-2 at home to CSKA in their first fixture.
In Group D Lille's compatriots Lyon tackle Dinamo Zagreb, while Real Madrid host Ajax, who they helped eliminate at the same stage of last season's competition.