Liverpool's return to European action for the first time in five years and Real Madrid's shaky start to the season dominate the start of the new battle for the Champions League title on Tuesday.
Liverpool take on surprise Bulgarian team Ludogorets Razgrad, while defending champions Real clash with Switzerland's Basel in the key matches of the first day.
German champions Bayern Munich play English counterparts Manchester City on Wednesday when Barcelona, Chelsea and Paris St Germain also set off on the gruelling campaign.
Only captain Steven Gerrard remains from the 18-man squad which featured in Liverpool's last Champions League match, a 2-1 loss at home to Fiorentina in December 2009.,
Manager Brendan Rodgers, who has spent big to bring in the likes of Italy striker Mario Balotelli and England midfielder Adam Lallana, says the side are not nervous about the return.
But as five times European champions Liverpool will have a lot to live up to.
"We have a very young squad and they will gain experience - it is about embracing it. There is certainly no fear of the competition," Rogers said on the eve of the match against the Bulgarian upstarts.
"I think success is about qualifying from the group. We will take one game at a time: we are at home in our first game and we aim to perform well and get three points but we will respect them like we would if we were playing Real Madrid."
Liverpool are in Group B with Real who also have a lot to prove to their fans after losing two Spanish league games in a row.
Despite the struggle, Real boss Carlo Ancelotti believes the defending champions remain the best in the European competition.
Madrid sold Angel di Maria and Xabi Alonso, but bought 75 million euro James Rodriguez and Toni Kroos to assist Cristiano Ronaldo in the hunt for goals.
"We have a lot of desire for this competition, we want to be competitive and try to win it again," Ancelotti said.
"It is a motivating factor to be competitive in the most important competition in the world. We have good memories of last season's competition and we will fight to repeat it this season. I wouldn't change this squad for any other in Europe."
Ancelotti has faced widespread calls to give Costa Rica World Cup star Keylor Navas his debut amid criticism of veteran club captain Iker Casillas.
Seventeen time Swedish champions Malmo FF make their debut in the Champions League at Italian giants Juventus in Group A, which also see Olympiakos of Greece take on Atletico Madrid, Spanish champions and beaten Champions League finalists last season.
Much focus will be on whether coach Diego Simone can maintain their dynamic form.
In Group C, Monaco play Bayer Leverkusen and Benfica entertain Russian league leaders Zenit St Petersburg, still looking for a return on their heavy spending.
Galatasaray of Turkey play Belgium's Anderlecht in Group D, which also sees Borussia Dortmund against Arsenal. Arsene Wenger's side beat Dortmund in last year's Champions League.
The Germans are without Mats Hummels and Marco Reus, but have been bolstered by the return of Shinji Kagawa from Manchester United who scored in a 3-1 win over Frieburg at the weekend.
In the second day of matches on Wednesday, Bayern Munich will also be looking for a German home win against Manchester City, Chelsea also face German opposition in Schalke, while Barcelona play Cypriot side APOEL and Ajax Amsterdam start against Paris St Germain.
The group games are the start of a long slog toward the Champions League final in Berlin on June 6.