Thirty years after the dawn of the modern Champions League, the group stage of this season's competition kicks off this week in the penultimate year in its current format, as Real Madrid begin their defence of the trophy.

Marseille were the champions in that inaugural 1992/93 season, but no French club has won the trophy since, and England, Spain, Italy and Germany have provided every winner since Jose Mourinho's Porto triumphed in 2004.

Indeed, since Inter triumphed in 2010, only five clubs have lifted the trophy –- Barcelona, Chelsea and Bayern Munich have been champions twice each, and Liverpool once.

Meanwhile, Madrid beat Liverpool 1-0 in Paris in May to be crowned European champions for the fifth time in nine years, confirming the enduring brilliance of veteran stars like Luka Modric and Karim Benzema.

They will set out with the aim of winning a 15th European Cup in Istanbul next June, with the group stage unlikely to overly trouble Carlo Ancelotti's side.

Real will face RB Leipzig, Celtic and Shakhtar Donetsk in Group F, fully aware that even a home defeat to Sheriff Tiraspol last year ultimately proved inconsequential.

"Last year the easiest game was supposedly against Sheriff at the Bernabeu and we lost it, so we need to respect these teams," Ancelotti told Spanish media.

He was also quick to point out another factor which could come into play this season.

Usually the group stage finishes in December, but the World Cup has forced UEFA to fit all six Champions League matchdays into a period of nine weeks starting earlier than usual.

"We will have to be ready not just for the quality of the opposition but also for the different demands and rhythms," said Liverpool manager Jurgen Klopp, whose team begin at Napoli on Wednesday as they look to put their defeat against Real in the final last May behind them.

It could be that the real impact of that is only felt when the knockout rounds start in February, when many players at Europe's biggest clubs will have had to come through the draining experience of a mid-season World Cup.

Nevertheless, the idea that someone from outside a narrow band of elite clubs might win the Champions League is fanciful.

Real will not start as favourites up against Manchester City and a reinforced Paris Saint-Germain in particular.

"The Champions League brings the best out of players, fans and teams. It would be very reductive to say that PSG are favourites," insisted PSG coach Christophe Galtier.

Liverpool and Bayern are also contenders, but the jury is out on Chelsea, Tottenham Hotspur or Barcelona.

From 2024 the group stage will be expanded to feature 36 clubs, up from 32, with all teams together in one pool and playing eight matches, instead of eight groups of four teams.

That will shake up a first phase that has become too predictable.

This time, most fascination lies in Group C, where Bayern, Barcelona and Inter Milan –- with 14 European Cups between them -– are together alongside Czech champions Viktoria Plzen.

It is quite possible that Barcelona, after a close season spent selling off assets to be able to strengthen their squad despite enormous debts, could be knocked out in the group stage for a second straight year.

"We got a very difficult group. Possibly the hardest of the last 20 years," warned Barcelona coach Xavi Hernandez.

While Barcelona have strengthened, even most clubs in the Champions League these days cannot keep their best players.

Not so long ago a group containing both Borussia Dortmund and Sevilla would be full of jeopardy for Manchester City.

Yet City themselves stripped Dortmund of Erling Haaland, while Sevilla lost their centre-back pairing from last season of Jules Kounde and Diego Carlos, and are weakened as a result.

That is just part of a pattern.

Ajax, in Group A with Liverpool, Napoli and Rangers, lost coach Erik ten Hag, Lisandro Martinez and Antony to Manchester United, and sold top scorer Sebastien Haller to Dortmund, amongst other departures.

Benfica face PSG, Juventus and Maccabi Haifa in Group H having sold leading marksman Darwin Nunez to Liverpool.

Their Lisbon rivals Sporting saw key midfielders Matheus Nunes and Joao Palhinha head to England, to Wolverhampton Wanderers and Fulham respectively.

Club Brugge, Salzburg and FC Copenhagen have all lost their top scorers from last season. So have Viktoria Plzen, whose French striker Jean-David Beauguel went to Saudi Arabia.

These clubs are all minnows in the Champions League pond, and most will be making up the numbers.