It's just shy of four months since Real Madrid lifted the European Cup for the 13th time in Kyiv, an unprecedented third Champions League triumph on the bounce.

It was the seventh time in the last decade that either Barcelona or Real got their paws on the trophy.

When you consider that six of the last ten Europa Leagues have been won by either Atletico Madrid or Sevilla, it's easy to see why La Liga aficionados bristle at the argument that the hugely hyped Premier League is where it's at.

Spain are producing the best of the best and the rest have work to do to disrupt their dominance.

Zinedine Zidane, the man who led Real to that historic trio of titles, stepped down after the win against Liverpool and they of course have lost their astonishingly prolific goal machine Ronaldo.

For so long Ronaldo and his great rival Leo Messi have defined the biggest and best European nights.

But is change in the air? New stars, fresh-faced managers and sophisticated philosophies are evident around the continent. And a lot of clubs have points to prove.

England hasn't had a Champions League winner since 2012, when Chelsea pulled off an absolute smash and grab against Bayern Munich. Manchester City look best equipped to change that, while Liverpool, Spurs, and Manchester United are all formidable.

Juventus are obsessed with conquering Europe and made a major statement by bringing Cristiano Ronaldo to Turin in the summer. And you can never write off the Germans...

We cast our eye on a few sub-plots worth watching over the next six months ahead of the first batch of group games this week.

Julian Nagelsmann's high-tech Hoffenheim

Julian Nagelsmann became the youngest manager in the history of the Bundesliga when he took the reins at Hoffenheim two years ago. He was 28 years old and earned the nickname 'Baby Mourinho' after transforming Hoffenheim's fortunes, turning them from relegation contenders into top-four challengers. 

That moniker feels ill-suited now that Nagelsmaan has crafted a style much more similar to the ways of Pep Guardiola, Thomas Tuchel, Arsene Wenger and Jurgen Klopp.

Hoffenheim were beaten by Liverpool in last year's play-off round but progress to the group stages for the first time in their history this year thanks to a third-placed league finish and the new UEFA rules that see the top four from four biggest leagues automatically qualify for group stages.

They're in a difficult Group F - alongside Pep's Manchester City, Shakhtar Donestk and Lyon. Still, the Germans will be well worth a watch. Nagelsmann loves thinking up sophisticated shapes and tactical set-ups, cultivating a thrillingly fluid 3-1-4-2 set-up.

Hoffenheim have also earned a reputation as one of the most innovative clubs in Europe when it comes to training methods. To hone technique and vision, they use the Footbonaut - a machine that spits out balls at different speeds and heights to players, who must kill it and pass it into a colour-highlighted square. Sort of like a football-themed Crystal Maze task.

Nagelsmann also erected an enormous video wall at the training ground and four cameras positioned around the pitch. It's used to show players exactly where he wants them to be positionally on the field and what to do in different situations. A step up from the salt and pepper shakers then. 

He's already already agreed to take over at RB Leipzig next season and his side have made a slow start to the league - one win and two defeats.

Still, don't expect Hoffenheim to park 10 men behind the ball when they square up to City. Nagelsmann's lads are here to play.

Inter return to the top table

Inter ended a six-season absence from the Champions League with an incredible final-day 3-2 win at Lazio which saw them leapfrog their opponents into the fourth and snatch the last qualification spot in Serie A. 

Mauro Icardi and Matias Vecino struck in the last 15 minutes to turn the game on its head and bring them back into the big time. They had a decent summer too.  

Radja Nainggolan had been reunited with Luciano Spalletti, who managed the tigerish Belgian midfielder at Roma, while Matteo Politano and Keita Balde give them some flair in the attacking positions.

But it never seems to be a smooth ride at Inter these days. 

The Nerazzurri were tipped as possible title contenders at the start of the campaign but after yesterday's 1-0 loss to Parma at the San Siro, they have now just four points from four matches.

They're in a devilishly difficult Group B alongside Barcelona, PSV Eindhoven and Spurs, who they host on Tuesday night.

But Inter are a club that belong with the elite. It may bring the best out of them.  

Is this Atletico's year?

Diego Simone has built one of the most respected sides in Europe over the last seven years.

Atletico, very much in the image of their coach, are horrible to play against, and have burnished their steel with players of class.

Beaten in the 2016 decider by their city rivals Real, that could have proven to be their peak, similar to Valencia after they lost their second decider in a row against Bayern Munich back in 2001. But Simeone has worked wonders to keep this bunch together.

After winning the Europa League last May and finishing runners-up in La Liga to Barcelona, they managed to hold on to prize asset Antoine Griezmann and then added serious ability to their wide positions with the acquisitions of Gelson Martins and Thomas Lemar. 

Simeone now has his most potent side yet; aligned with the Argentinian's superb organisational ability and ruthless, insatiable greed for silver, they will be a massive thorn in the side for any team in this competition.

Another year, another 'dark horses' tag, but Atletico are cute enough and experienced enough to have learned from past failures. 

They have three World Cup winners in their ranks - Griezmann, Lucas and Lemar - and next May's decider is at their own stadium, the spectacular Wanda Metropolitano. Is it written in the stars?

How good can Kylian Mbappe be?

The French prodigy burst on to the scene two years ago on that fantastically entertaining Monaco team who made it to the Champions League semi-finals.

Still only 19, he already has a World Cup winner's medal in his pocket and now takes pride of place in PSG's star-studded outfit. 

For so long Messi and Ronaldo have set the bar for everyone else but their greatness cannot last forever. Neymar left the Nou Camp to get out of Messi's shadow but his reputation has been tarnished by petulance, play-acting and inconsistency.

The real star in Paris is Mbappe.

PSG go to Liverpool on Tuesday night for what we hope will be a memorable, high-octane shootout. Mbappe, Neymar, Cavani, Salah, Mane, and Firmino all on the same pitch? It's mouthwatering.

And that's not to mention the match-up on the touchline, with compatriots Tuchel and Klopp set for a battle of wits.

There's few more thrilling sights than Mbappe in full flow and he could light up Anfield on Tuesday night. He's the obvious heir to Messi and Ronaldo's shared throne. 

Who will fill Ronaldo's shoes?

The push for glory never stops at the Bernabeu; nor does the search for the globe's next superstar. They got their money's worth out of Cristiano Ronaldo. The Portuguese came from Manchester United for £80m back in 2009 and was sold on to Juve for nearly £100m nine years later.

In between he scored 451 goals to become the club's all-time highest scorer, winning two La Liga titles and four Champions Leagues. Not bad. And his departure leaves a pretty big void to fill.

Gareth Bale has long been mooted as the heir to Cristiano's throne and will be expected to have more influence this year. The Welshman is for today though. Tomorrow belongs to the new kid in town.

Eighteen-year-old Brazilian prodigy Vinicius Junior arrived from Flamengo for €43.5m in July and was heralded by Real president Florentino Perez as "a player who is already considered one of the great hopes of Brazilian and world football".

Blessed with mesmeric dribbling skill the attacker is an extremely exciting prospect. Just how he handles the incredibly intense glare of the spotlight at a behemoth of a club will be key.

Real are happy to nurture Vinicius' talent in their Castilla reserve team for now. But we might get a few European cameos to show us what all the fuss is about.

Watch Liverpool v PSG live on RTÉ2 and the RTÉ Player on Tuesday from 7pm