IT has finally happened. After three years of European domination, Real Madrid have been knocked out of the Champions League. Lifting the famous trophy for a fourth straight season was always going to be a big ask for the European champions, but few would have predicted that they would fall short at such an early stage of the season.

Ajax put in a tremendous display at the Bernabeu last night in a wonderful throwback to their glorious past. This side might not be quite at the level of the famous 1995 side that featured the likes of Clarence Seedorf, Edwin van der Sar and the De Boer brothers but the result will go down as one of the finest in the Dutch club’s illustrious history.

The game on Tuesday night has understandably got fans of Ajax - and indeed, neutrals as well - excited about the club’s prospects between now and the end of the season. There is a palpable feeling in this year’s Champions League that the tournament that has so often been criticised for the dominance of a few select clubs could throw up a new winner this time around.

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A look at the clubs left in Europe’s premier club competition doesn’t throw out any obvious candidates for success this year. Barcelona will probably be the favourites, but they still have to navigate a very tricky tie against Lyon - a team who have repeatedly shown that they are capable of causing an upset or two this season. Paris Saint Germain’s sole league defeat this season came at the Stade Gerland, and Lyon beat Manchester City 2-1 at the Etihad. They face Barcelona at the Nou Camp next week with the tie still goalless and although the home side are the favourites, a win for the underdogs would not be surprising.

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Barcelona are certainly impressive, but Ernesto Valverde is yet to fully convince as manager at the Nou Camp. Lionel Messi has been back to his imperious best and has often carried Barcelona through matches this season, but even Messi is human and will surely have an off-day eventually. When that day arrives, Barcelona will look vulnerable indeed.

The other perennial pre-tournament favourites, Bayern Munich, are themselves undergoing a season of transition under the guidance of Niko Kovac and do not look quite as fearsome as they have in previous years. The Bavarian side are level on points with Bundesliga leaders Borussia Dortmund but have suffered from several hiccups this season and look far from invincible. Liverpool travel to Munich next week in a tie that again could go either way, but where the hosts are probably slight favourites.

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There is a vacuum at the summit of European football, that only a couple of seasons ago a handful of clubs occupied. Barcelona, Real Madrid and Bayern Munich were a level or two above everybody else but now that chasm has closed. All three look beatable and there are no outstanding sides in the Champions League this season. Even Juventus, who have looked the most likely side in recent seasons to break into this exclusive group, are on the brink of elimination, trailing Atletico Madrid 2-0 ahead of the return leg in Turin next Tuesday evening.

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This fallibility that is apparent in Europe’s top sides will be music to the ears of two relative newcomers to Europe’s top table. Paris Saint Germain and Manchester City will both be encouraged Madrid and Bayern’s fall from grace and will surely be looking to capitalise on the open nature of this year’s competition. These two nouveau riche clubs are desperate to lift the Champions League trophy in order to truly be considered part of football’s elite and both are arguably in the best shape they have ever been in this European campaign.

Then there's Atletico, who have an unparalleled ability to grind out a win over anyone, and a Spurs side that can give any opposition a headache. Even Roma showed that they are capable of sustaining a decent run in the tournament, having reached the semi-finals last time around. Teams like Tottenham and Roma are outside bets at this stage of the tournament, yet still have enough clout that they cannot be written off as possible contenders. The gap between the top sides and the rest has narrowed, and the Champions League is better for it.

With the knockout rounds well and truly underway, this year’s Champions League feels a bit different to previous iterations. For most of the last decade, it seemed as if there were only a small handful of clubs capable of lifting European football’s biggest prize. The door is now open for a newcomer to make their mark on the Champions League, and the competition feels a whole lot fresher for it.