From Barcelona to Mourinho: The 10 biggest disappointments of the Champions League in 2017-18

Barcelona recorded a domestic double, with their only defeat in La Liga coming after they had already wrapped up the title. 

The 2017-18 season must go down as a success for new coach Ernesto Valverde, who helped the Catalan club recover from the shock loss of Neymar to PSG, and a resounding and concerning Supercopa defeat by Real Madrid.

However, Barca once again came up short in the Champions League. Their second-leg collapse at the Stadio Olimpico was undoubtedly shocking but that they were beaten away from home was wholly unsurprising.

Indeed, Barca have lost four of their past five away games in the knockout stage, by a combined score of 0-12, with their only goal coming in a 1-1 draw at Chelsea in this season's last 16.

The Catalans, thus, have serious issues to address, both in attack and defence, if they are to challenge for a sixth European Cup next year.

One can understand why Juventus Gianluigi Buffon reacted so emotionally to Michael Oliver awarding Real Madrid a contentious penalty in the dying seconds of normal time in an absorbing quarter-final second-leg clash at the Santiago Bernabeu. 

After wiping out a 3-0 deficit, the Bianconeri deserved extra time and were understandably crushed when it became apparent they would instead be eliminated by a penalty from the nerveless Cristiano Ronaldo. 

However, Buffon nonetheless stepped over the line with his furious outburst at the match official. Even then, it could have been dismissed as 'heat-of-the-moment' stuff but Buffon made matters far worse by launching into a very public tirade against Oliver after the full-time whistle.

It was most unbecoming of a man who has always been renowned for his sense of sportsmanship and fair play, and the hypocrisy of the Juve captain complaining so furiously about a referee's decisions was not lost on the supporters of Old Lady's many rivals.

Thankfully, the goalkeeping great belatedly apologised for saying Oliver had a "dustbin for a heart" but by that stage, the damage had been done, both to Oliver, who was subjected to death threats, and Buffon's reputation.

This was meant to be Paris Saint-Germain's year.

Last summer, the Qatari-funded club obliterated the transfer fee world record by paying €222 million to secure the release of Neymar from his Barcelona contract, before then taking Kylian Mbappe on loan from Monaco on the proviso that they would sign the teenage sensation at the end of the season for approximately €180m.

It was clear that PSG, more than ever before, had the players to win the Champions League. Unfortunately, it ultimately transpired that they still don't have the requisite character.

A year after their embarrassing capitulation at Camp Nou, they suffered a meek exit at the hands of Real Madrid at the same stage. 

Neymar's injury played a part of course but, during that dismal second-leg loss at the Parc des Princes, it was clear that PSG still had neither the intelligence (see Marco Verratti's stupid sending-off) nor the bravery (see Unai Emery's negative tactics) to win the club game's most prestigious prize.

With Neymar having already grown tired of Paris, and Thomas Tuchel feeling like a rather uninspiring replacement for Emery, PSG's Champions League-obsessed owners have a tough job on their hands convincing the footballing world that their plans for world domination can still be realised.

Paulo Dybala is a lucky boy.

The Juventus striker may have netted a career-high 22 Serie A goals this season but he did not play with anything like the same consistency as Mauro Icardi, yet he made the Argentina squad for this summer's World Cup while his compatriot did not.

Furthermore, while Inter captain Icardi inspired his side to Champions League qualification, Dybala deserted his team when they needed him most, in the first leg of the Champions League quarter-final clash with Real Madrid.

Dybala's senseless dismissal for a second yellow card paved the way for a rampant Blancos side to rack up a third unanswered goal in Turin, which ultimately proved decisive. 

Argentina boss Jorge Sampaoli has called Dybala an "anarchic talent" and it is a fair point: it is high time that the 24-year-old complements his exceptional skills and wonderful left foot with greater composure and consistency.

VAR is by no means flawless. During Saturday's FA Cup final, Ashley Young got away with a clear handball even though the Manchester United defender had clearly motioned towards the ball with his left arm. 

However, thanks to VAR, officials in Serie A benefited enormously from video assistance this season, righting a number of wrongs. 

It was, thus, easy to understand the frustration of Roma president James Pallotta after seeing his side narrowly fail to overturn a 5-2 first-leg deficit in a game in which his side were denied two clear penalties, one of which would have resulted in a red card for Liverpool's Trent Alexander-Arnold.

The American opined, "If we don't get VAR in the Champions League, it will be an absolute joke."

Improvements still need to be made - particularly in terms of transparency and the time involved - but it's hard to disagree with Pallotta's opinion.

Manchester City boss Pep Guardiola couldn't say enough nice things about Maurizio Sarri's slick Napoli side. 

However, the Partenopei's dismal group-stage exit only strengthened the argument held by some critics that the Italians are all style and no substance.

The truth of the matter is a little more complex than that, given Serie A was Napoli's priority this season, which resulted in Sarri trying to occasionally rest the key members of a limited squad. 

Still, to see Napoli bow out after losing four of their six games in a group that also featured Shakhtar Donetsk and Feyenoord cannot be classed as anything other than a major let-down. 

Jose Mourinho upset Manchester United fans by describing the club's last-16 exit, after a tame 2-1 loss at home to Sevilla, as "nothing new".

However, the Portuguese manager was right in a sense: a performance of such atrocious negativity was certainly nothing new in terms of his Old Trafford tenure.

The ends always justifies the means as far as Mourinho is concerned but when he fails to deliver trophies, his methods are made to look horribly outdated, and particularly ill-fitting at a club renowned for attacking football.

Mourinho subsequently launched an impassioned, 12-minute defence of his comments but there were obvious comparisons between this "football heritage" speech and Rafael Benitez's infamous "stats" rant. 

The latter outburst essentially signalled the end of the Spaniard's time at Anfield and one wonders if Mourinho's lecture will be remembered in the same way, given he is under fire again after paying for a negative approach in the first half of Saturday's FA Cup loss to Chelsea.

Neymar is by no means the only footballer to dive. Indeed, it must be recognised that he is often targeted by opponents, given he is one of the most talented players in the game.

However, one could understand why Celtic's Anthony Ralston laughed in the face of the PSG winger - who had already been booked for diving - as he rolled around on the grass looking for a free-kick during their group-stage encounter in Glasgow.

Neymar, though, didn't see the funny side and refused to shake Ralston's hand after the game, which only cast the brilliant but childish Brazilian in an even more unfavourable light. 

Ultimately, though, the authorities are the ones to blame for the likes of Neymar continuing to make fools out of referees with his theatrics.

Celtic's Mikael Lustig was right when he mused, "If Neymar wants to be liked as much as Messi, maybe he needs to stop all of that."

This has been a wonderfully enjoyable Champions League, full of memorable matches and great goals.

However, while we have seen some fantastic forward play, some of the defending has been dire. 

Chelsea gifted Barcelona a place in the last 16, Barcelona suffered a collective blackout in Rome, Bayern Munich beat themselves in their semi-final showdown with Real, while Roma even seemed utterly unfamiliar with their former player, Mohamed Salah, let alone any of his fellow Liverpool attackers in their meeting at Anfield.

All of those games were great fun to watch but did absolutely nothing to dispel the mounting suspicion that, Atletico Madrid aside, the art of defending is dead.

Professional football would be nothing without the fans. They fund the entire enterprise. However, their willingness to hand over hard-earned money to watch their team in action is not rewarded, it is exploited.

The supporters are an integral part of the spectacle yet treated like an after-thought. Nobody would argue against Kiev's right to stage this season's Champions League final but there has been zero consideration for the supporters in terms of logistics and travel costs.

Thomas Cook Sport were forced to lease extra aircraft to meet the demand among Liverpool fans for flights to Ukraine and that has resulted in some tickets going for as much as £1,000.

Meanwhile, an estimated 2,200 Real Madrid fans had to return their tickets because they could not afford to travel to Kiev. That is a disgraceful state of affairs. 

But then, who cares? UEFA certainly doesn't seem to, given the European game's governing body only allocated 33,252 tickets to the finalists, with a further 6,700 put on general sale.

That means that of the 63,000 people set to be present at the NSC Olimpiyskiy Stadium on Saturday, 37 per cent of the attendance will be made up by hospitality members, rights holders, commercial partners and officials.

As a result, tickets have become so scarce that they are going up for as much as £14,000 on resale websites, a practice that has been banned in England since 1994. 

The whole situation is a farce and only serves to underline that football is no longer the people's game; it is a brutal business.