As expected, Barcelona delivered the goods in last night’s Champions League quarter-final, second leg tie against AC Milan at the Nou Camp.

On paper, the 3-1 victory appears pretty standard for the Spanish and European champions, who have claimed the ultimate crown on this continent twice in three years under Pep Guardiola. They are now three games away from another success.

But, once again, a slightly sour taste has been left in the mouth after another hugely controversial decision went the way of the Blaugrana.

With the scores level at 1-1, referee Bjorn Kuipers gave the hosts a penalty for Alessandro Nesta’s off-the-ball shirt pull at a corner. It was an intriguing decision for a number of reasons.

Firstly, the corner had literally just been taken. We’re talking about a fraction of a second after the kick before the decision was made. Additionally, these kind of incidents happen all the time in the box on corners. Sergio Busquets didn’t need a second invitation to throw himself to the floor – much like Lionel Messi when he was fouled for the first penalty.

It’s these theatrics Barcelona continue to produce which are losing them their global admiration, and former striker Zlatan Ibrahimovic was understandably frustrated at the second decision.

"I'm just disgusted. They are the best team in the world but at 1-1 and, playing with intelligence, you can do something,” said the Swede post-match.

“I understand better why Mourinho gets upset every time he plays here - in my opinion it was not fair. If he calls those he should call the others. Without him the game would have been 50-50."

That has to be the biggest argument against the decision made by the referee – he must give penalty decisions at every corner if he is to punish an act of shirt pulling. You can have no arguments with an official if they are consistent with their decisions.

"Sometimes the referee made too many concessions. I don't know if it proved decisive. We made a mistake on the first penalty but he helped on the second. Playing Barca is never easy," added Milan boss Massimiliano Allegri after the game.

So is it just a case of sour grapes? History would suggest not, with a handful of teams now holding a grudge against the best team in the world because of questionable decisions.

Unsurprisingly, Real Madrid boss Jose Mourinho is one of those to have a particular problem with the way things have gone down against the Catalonian giants, having fallen victim on two occasions – with Chelsea in 2009 and Real Madrid last season.

“I don't know if it's to give publicity to Unicef or their power at UEFA. I don't know if people just like them. I don't know and I don't understand. Where does all this power come from? No-one else has a chance really,” said the Portuguese manager after a semi-final first leg defeat at the Bernabeu.

“Why don't they let other teams play against them? If Barcelona are honest, they know this is happening.”

‘The Special One’ was referring to referee Wolfgang Stark’s decision to send off defender Pepe at 0-0 in the tie, with Barca going on to win the match 2-0. Contact with Dani Alves appeared minimal, and as the Brazilian defender rolled on the floor, a red card was duly delivered.

At Stamford Bridge two years earlier, Tom Henning Ovrebo turned down five legitimate penalty appeals from Chelsea as they drew 1-1 with Barca in a semi-final second leg, knocked out on away goals. It was a quite baffling performance from the official, who cost the Blues a second crack at Manchester United in a final.

Don’t forget to add Arsenal to the list of victims, after Massimo Busacca handed Robin Van Persie a second yellow card for ‘deliberate time wasting’ in the Camp Nou. His shot, literally a second after the whistle, was too much for the referee, handing Barca the initiative whilst trailing 3-2 on aggregate.

“When it was 1-1, it was all to play for. In my opinion, the referee killed the game. It had a big influence on the result,” said the Dutch striker post-match. Arsene Wenger also received a UEFA fine and ban for his comments.

What’s frustrating for the neutral is that, for all their brilliance, these moments of controversy are taking away from the long-term legacy that Guardiola has done so well to build upon in Spain.

The former midfielder has managed to take his side to the next level, from one of the top two clubs domestically to the very best team in world football. Two Club World Cups go some way to proving that fact.

However, an in-ability to avoid high drama is understandably working against Barcelona.

Without the second penalty against AC Milan, the probability is they would have won the match anyway. The same can be said of all the other matches previously highlighted, with the exception of that fateful clash against Chelsea in west London.

And, whilst Barcelona can’t help it if refereeing decisions go their way, they can affect their own perception on the pitch, which is being undermined by play acting and flare-ups on a regular basis in European competition.

Through all the wrong decisions, we should not lose sight of the fact that Barcelona are probably the best team we will ever see assembled. But, they must start to carry themselves like champions in order to receive global acclaim from their harshest critics.