Eighteen games played simultaneously, endless permutations and the sort of jeopardy that the Champions League has long craved. It was a chaotic night in Europe and UEFA will doubtless conclude that the so-called Swiss system has delivered on its promise.

Following events from inside Villa Park as Aston Villa played Celtic amid a frenzied atmosphere was a joyful football experience but there was still the nagging sense that this was an occasion designed for television or online rather than the match-goer.

The days of transistor radios are gone but even when domestic leagues have been dictated by events elsewhere there has usually only been one other result to worry about. In a 36-team league, keeping track of the possibilities was all but impossible.

For most, it will have added to the fun. With only six points separating sides ranked third to 23rd in the table going into the final round, the uncertainty was part of the thrill. Some of the teams involved could not be sure of their fate with just minutes to go.

Manchester City, champions of Europe in 2023, looked to be the story with 15 of their 16 halves of football played in this league phase as an early exit loomed. They salvaged it in the second half. Sporting were out then in. Dinamo Zagreb were denied progression late on.

At Villa Park, even as a thrilling contest gripped the fans in the Holte End and elsewhere, others were frantically calculating what an Atalanta goal might mean to the home side's prospects of a top-eight finish. Each goal from another game flashed up on the screens.

Perhaps it was a faux-jeopardy in the end. Nine of the 12 teams actually eliminated from the competition knew the score before the last matchday, none of them true giants. And the prospect of a play-off bothers coaches more than the clubs' bean counters.

But there is no need to be too churlish when it did feel like an improvement. Liverpool and Inter Milan were the only two of the previous 10 Champions League finalists among the top eight in the end. This was no procession for most, more like a maze to negotiate.

And it had become a procession. City had successfully navigated the old group stage 11 times in a row. This was more fraught. Maybe that owes something to their form but Bayern Munich and Real Madrid began the evening down in 15th and 16th respectively.

That put them below a trio of French clubs - none of which were Paris Saint-Germain. Their comeback against City on the penultimate matchday meant a draw would be enough for PSG and opponents Stuttgart - but they put four past the German side.

Much of the excitement stemmed from the unknown. Few knew what to make of it. Upon finding out that his team were sure of a top-eight finish, Liverpool boss Arne Slot had said: "That is the only thing that tells me something because this league table doesn't."

But it is about the journey as well as the outcome. For supporters, eight opponents rather than three in the opening phase brought greater variety. It may have raised issues of fairness but, in truth, that home-and-away group format had come to feel outdated.

Arsenal made light work of it in the end but they had to go to Atalanta first up and then played PSG and Inter before mid-November. "Usually you would find these games in the quarter-finals or semi-finals," said their midfielder Declan Rice - and he had a point.

The driving force behind the format change was to guarantee more such games for Europe's elite, a response to the breakaway Super League plans. Increasing the risk for the continent's richest clubs was not the intention but the outcome was encouraging.

Some will be sceptical about that conclusion given Manchester City's progression despite winning only three of their eight matches. Ultimately, the biggest casualty of the league phase was probably Stuttgart - and it took 144 matches to eliminate them.

But the threat to the European heavyweights was there. Perhaps it even encouraged an attacking approach given that denying the opponents is not so helpful when a draw can see you tumble down the table. "This format forces us to win," said Diego Simeone.

There were still the hammerings. Bayern Munich's 9-2 win over Dinamo Zagreb on the opening matchday was an ominous sign, laying bare the disparity between east and west - the eight teams east of Munich on the map were among the dozen knocked out.

But the chaotic results were a boon too. Borussia Dortmund put seven past Celtic, who then went on a five-game unbeaten run of their own. Even Red Star Belgrade won 5-1 against Stuttgart. And then there were the closer contests and the turnarounds.

Dortmund led by two in the Bernabeu before being beaten 5-2 by Real Madrid. AC Milan did beat the 14-time European champions there. Barcelona won 5-4 at Benfica in an extraordinary game, while Sporting beat Man City 4-1 as Ruben Amorim bade farewell.

Personal memories include being inside the Parc des Princes to see Atletico Madrid's stoppage-time winner against Paris Saint-Germain and witnessing that astonishing Feyenoord comeback from three down at the Etihad to leave Pep Guardiola bereft.

Such moments buoyed a potentially bloated league phase and one wonders how much of its success was owed to that novelty factor. Was it true jeopardy that provided the momentum or just the ongoing uncertainty over where exactly each team stood?

For now, the Champions League feels reinvigorated enough for it to be seen as a success. And with the best teams in Europe still going into February believing they can get their hands on Old Big Ears in May, UEFA will regard this as mission accomplished.