After Barcelona and Manchester City crashed out of the Champions League despite spectacular league campaigns, Guillem Balague asks: How do we define success?
The Champions League is a competition that has always thrown up a number of surprises. But what is most interesting is a new trend; teams that make the most impact during their league campaign seem to be running out of steam as the "squeaky bum time" of Europe's most prestigious knockout tournaments loom into view.
Manchester City, Barcelona and Juventus are all flying high on the domestic front. Only Bayern Munich, already crowned Bundesliga champions for the sixth year running, have bucked the trend and they can now focus their undivided attention on the Champions League and, as a bonus, an upcoming German Cup semi-final against Bayer Leverkusen next Tuesday.
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Liverpool (17 points behind City) and Roma (21 points behind Juventus) were joined in the last four Bayern and Real Madrid (15 points behind Barcelona).
But why have so many of the dominant European sides failed to step up to the European plate? Why have they failed to find that extra gear?
City gave us an explosive start on Tuesday, an early goal and a fine first half that promised fireworks, before party-pooper in chief, Mo Salah - who else? - scored the goal that effectively finished the match as a contest. Liverpool's second goal from Roberto Firmino merely rubbed salt into the wound.
Pep Guardiola demands his team to be focused for 90-odd minutes to create the complex relationships that are demanded for the brand of football he wants to produce, and has regularly produced this season. But no team has ever kept complete concentration during a whole game.
Jurgen Klopp, intelligently, did not need his team to 'flow', only to identify the moments of weaknesses and exploit them, and Liverpool did that brilliantly. Klopp said after the game he still thinks City are the best team in the world as he is aware, as all coaches are, of how complex it is to create the patterns that make City so beautiful and special.
So, taking absolutely nothing aside from Klopp and how he masterfully used the team he is working with, more modest than others that are fighting with Liverpool for titles, is this perhaps a time to look again at what we consider success to be? Or even better, should we be talking about different measures of success?
Both City and Barcelona's seasons are now being judged by their latest results, although the fact is that both of them, barring meteoric collapses in form, are going to win their respective league titles easily.
And if winning your domestic title is not an indicator that you are the best in your country, what exactly is?
In truth, aside from the platitudes and clichés that proclaim that cup tournaments are a sprint while league campaigns are a marathon, what they normally tell us is that while a league table will show what the best team in a particular country is, tournaments like the Champions League point out the best team in the Champions League in any given year.
Perhaps, even more simply, it tells us who can produce the goods when it comes to a knockout competition. And that is also important. It tells us who has the character to function under pressure and who comes short at that crucial point.
Also winning the Champions League requires different weapons and constituents to those needed to win the league, not least of which is luck, the rub of the green.
Key decisions can even out over the course of a 38-game season, while on a crucial two-legged, blood-and-thunder Champions League quarter-final, they can kill you.
Pep Guardiola wasn't moaning about the refereeing performance per se, but merely stating the obvious in that, sometimes the fickle finger of fate is with you - remember Barcelona's semi-final against Chelsea in 2009 with a host of rejected penalty claims and a last-gasp decider by Andres Iniesta?
And sometimes it isn't with you - Salah's marginal offside goal in the first leg and Leroy Sane's disallowed goal in the second. On such details are destinies decided; that's one of the main reasons why we love - and occasionally, hate - this game so much.
"Also winning the Champions League requires different weapons and constituents to those needed to win the league, not least of which is luck, the rub of the green."
Aside from that what can't speak, can't lie. The record books will show a 5-1 aggregate win for Liverpool, a win that came about because at the key moments Liverpool were there and City were not.
In the case of Barcelona - and I have been saying this for a long time now - despite what the league table may show us, this is the worst Barcelona, certainly in squad terms, I have seen for a decade. To date, the club has been saved by the astute decision-making of Ernesto Valverde and on the pitch by Marc-Andre ter Stegen at one end and by Leo Messi at the other. That is what you get by having the best player in the world - it hides over cracks and blurs the picture.
The day that Messi fails to look like the best player in the world, everything seems to collapse around them.
A 4-1 scoreline in Barcelona's home first-leg victory over Roma flattered to deceive. Messi did not have the best of games and in Rome they were unable to handle the pressure, and physicality, of their Italian opponents. On Tuesday night the chickens well and truly came home to roost.
Sergio Busquets has described it as his worst ever result in football, but he is an intelligent man and he will know that while the club to date had not suffered such a humiliating reversal since the start of the season in the Spanish Supercup against Real Madrid, it was always something one felt was 'in the post'.
"Despite what the league table may show us, this is the worst Barcelona, certainly in squad terms, I have seen for a decade."
The finger-pointing has begun. Nelson Semedo is one of those being singled out for particular criticism, as is central defender Samuel Umtiti, and even Luis Suarez, who was almost invisible both as an attacking force or as someone prepared to track back to help his team in a defensive capacity. More worryingly, Valverde is on the receiving end of the resulting vitriol from within the team where some of the players are far from impressed with his plans to reduce his reliance on possession football.
I'm not sure I agree with that. Valverde is nothing if not a pragmatist. If he is relying less and less on that type of game it is because he knows the limitations of his squad.
While no side should ever be regarded as a one-man team, in recent times Barcelona and Leo Messi are about as close as you'll ever get to witnessing that particular scenario, not merely because of how the side plays when he does 'turn up', but more specifically how things pan out when he doesn't.
They could still win the Cup and League double but that does not get away from the fact that, both physically and mentally, this is now a slightly tired, stale-looking Leo Messi that Barcelona have an over-reliance on.