Real Madrid are the most successful side in both the European Cup and Champions League history and are the current holders following their 4-1 triumph over Juventus in June 2017.
Barcelona aren't far behind and there have been many dominant sides over the past 25 years, including Bayern Munich, Manchester United and Milan, but who would be top dog if they faced one another in a winner's winner tournament?
Jose Mourinho led his Porto side to an unlikely Champions League victory where they overcame Monaco in Gelsenkirchen. The Portuguese outfit were going through a purple patch after securing the UEFA Cup during the previous campaign.
Mourinho was considered a rising star in the world of management and his side featured talented players such as Deco, Pedro Mendes, Nuno Valente and Carlos Alberto, although few would have predicted their success in this competition. Monaco weren't helped when their captain Ludovic Guily limped off after 22 minutes but Mourinho's tactical mastery has to be applauded.
This Porto side would give any other Champions League winning side a run for its money and Mourinho has built a reputation for being able to stifle quality opposition. They are unlikely to be eliminated in the first round of the winners' winner tournament but even with Mourinho's magic, they could fall short.
Porto have played 170 Champions League matches and are still a regular fixture in the competition but they aren't quite as powerful these days and, as of October 20th, are priced at 400/1 with 888Sport for success in the competition.
Chelsea are another side who forged their way to an unexpected success in the Champions League under Roberto Di Matteo. The Blues had finished top of their group before sneaking past Napoli in extra time. Benfica and Barcelona were subsequently eliminated during an impressive run but they were priced up as huge underdogs to beat Bayern Munich at the Allianz Arena.
Home advantage was expected to be decisive and with John Terry absent from the Premier League side, they were tipped to struggle. However, that script was well and truly ripped up as they triumphed via a penalty shoot-out with Bastian Schweinsteiger missing the key spot-kick.
Many pundits feel that Chelsea were lucky to reach the final but their determination was admirable and they could be plucky underdogs once again in the winner's winner tournament. However, they might just lack the quality to make an impact although Didier Drogba will once again prove their star man.
Chelsea have made a decent start to the 2017-18 Champions League and look set to progress to the knock-out round. They are 17/1 with 888Sport to replicate their 2012 success as of October 20th.
Milan were one of the best sides to watch during the 1990s and their mesmeric performances earned them a worldwide fanbase. Those supporters were treated to a masterclass in the 1994 Champions League final as Barcelona were torn apart in Athens. They kept consecutive clean sheets in the semi-finals and final with Marcel Desailly leading by example.
It was one of their three Champions League titles but Fabio Capello's men put in arguably one of the best team performances seen in the competition. Daniele Massaro's superb goal set them on their way with the Italian netting two of his four tournament goals in the showpiece event.
This Milan side could blow away a fair few sides in the Champions League winner's winner tournament and could be a force to be reckoned with. They played without the suspended Franco Baresi and were still strong enough to put Johan Cruyff's side to the sword.
Milan have suffered a downturn in form over the past couple of years but they have qualified for the Europa League and have begun well. At the time of writing, they are joint-favourites for the Thursday night competition at 6/1 with 888Sport.
Bayern Munich (2012-13)
Despite playing 221 times in the competition, Bayern have only ever won two titles, with the 2013 final remembered for being an all-German battle held at Wembley. Borussia Dortmund were on a roll under Jurgen Klopp and were playing some eye-catching football.
Whilst many neutrals would have been cheering Dortmund to success, Bayern proved their credentials on the biggest stage. They needed extra time to secure the victory, however, but it was the instrumental Arjen Robben who made the difference and secured the man of the match award in the process.
The Dutchman was joined by Bastian Schweinsteiger, Franck Ribery and Mario Mandzukic in a side who had previously ousted Barcelona and Juventus from the competition.
This Bayern squad was packed full of talent and had goals in abundance with a number of players at their peak. Unfortunately, they are likely to fall agonisingly short in the Champions League winners' winner tournament but they could pull off a few surprises along the way.
Despite being drawn in a group with big-spending PSG, Bayern look set to progress to the knock-out stage of the 2017-18 competition and are 15/2 to recreate their 2013 success.
Real Madrid (2016-17)
With six titles in 21 stagings of the competition, Real Madrid remain the most decorated side in the Champions League and there are a number of their squads who could feature in the winners' winner tournament. The latest success was particularly notable for the sheer ruthlessness of their performance as they battered a previously stubborn Juventus side.
The Serie A giants had already kept two clean sheets against Ligue 1 champions Monaco and Barclona but failed to stop the Real Madrid bandwagon which scored four times en-route to glory in Cardiff. Zidane, who was toasting success during his first season in charge had already guided his side to victories over Atletico, Bayern Munich and Napoli - a ridiculously difficult run of games.
Cristiano Ronaldo was once again at the epicentre of every Real attack and he was joined on the scoresheet by Asensio and Casemiro. This was an incredibly swashbuckling and eye-catching performance from a talented side and they would be worthy contenders for a place in the winner's winner final.
Unsurprisingly, Real Madrid have been installed as 4/1 favourites to retain their Champions League crown this season.
Manchester United (1998-99)
The first of Manchester United's two triumphs in the Champions League is remembered for its dramatic conclusion as two stoppage-time goals secured the trophy for the Premier League side. Sir Alex Ferguson's side looked devoid of ideas as they desperately searched for a way back into the match against Bayern Munich.
Teddy Sheringham and resident super-sub Ole Gunnar Solskjaer entered the field and completely tipped the match in their team's favour. United had arguably the tougher passage to the final having seen off Juventus and Napoli, whilst their opponents have walloped both Kaiserslautern and Dynamo Kiev.
This Manchester United team are a side who never knew when they were beaten but they can't pull off this trick continually and against some of Europe's great, the likes of Jesper Blomqvist and Dwight Yorke may be found out. Unfortunately, they may struggle in the winner's winner tournament although they won't go down without a fight.
The Red Devils have equipped themselves well during their first season back in the Champions League and are 14/1 to go all the way.
No Champions League list is complete without the inclusion of Barcelona. Barca are synonymous with glory in this competition and one of their greatest displays came back in 2011 when they easily swept aside Manchester United. The Premier League side were a terrific team and deserved their place in the final but the Catalan club were just a cut above.
After beating La Liga rivals Real Madrid in the semi-final, Lionel Messi and co set to work on Sir Alex Ferguson's side. The Argentinean picked up the man of the match award and scored one of the three goals at Wembley. Xavi and Andres Iniesta were unplayable in the middle whilst Gerard Pique and Javier Mascherano ran a tight ship at the back.
This Barcelona team had 19 shots during the 90 minutes and left many Manchester United players looking hopelessly at one another. The Blaugrana were superb and it's hard to see who will stop them in the winner's winner competition.
Barcelona are still adapting to life under new coach Ernesto Valverde but they are still fancied to progress in the competition this season with 888Sport pricing them up as 15/2 shots for the tournament.
Milan were entering their third consecutive Champions League final and were expected to triumph but Dutch outfit Ajax had other ideas. They hadn't previously triumphed in this competition but a superb performance against Bayern Munich in the semi-finals gave them the opportunity to add their name to the already-impressive roster of tournament winners.
Milan dominated proceedings but the experienced Frank Rijkaard grabbed the game by the scruff of the neck and fed Patrick Kluivert who netted the winner five minutes from time. Despite their abundance of talent, Milan had no response and Ajax got their hands on the trophy.
Louis Van Gaal's side certainly had a fearless approach to games and they dispatched Milan, but the fact they weren't able to add further Champions League is likely to count against them in the winners' winner tournament.
Unfortunately, Ajax have not qualified for a European competition this season but are priced as second-favourites for the Eredivisie title in the Netherlands at the time of publication.
There is a huge amount of quality on show and every Champions League fan is likely to have a differing opinion on how each side would fare in the winners' winner competition.
Chelsea, Manchester United and Porto are all likely to just fall short whilst Milan and Ajax will reach the latter stages of the tournament, but it's hard to ignore the power and dominance of the two La Liga sides in the Champions League and a Barcelona versus Real Madrid final is a likely outcome, with the classy Catalan side narrowly edging out Zidane's men.
2. Real Madrid
3. Bayern Munich
7. Man United
*Odds subject to change - correct at time of writing*