Perhaps it comes with the territory. The most successful sides are always accused of benefitting from favours and, in Europe, there is no more successful side than Real Madrid.
Los Blancos have won the European Cup 12 times, including the first five editions of the continental competition and even back then, their wins were arousing suspicion.
The club's former president, Santiago Bernabeu, was a driving force in the creation of the European Cup and in the first edition, Real Madrid were given the choice of opponent. They picked Servette from Geneva (sixth in the league that season) because Bernabeu wanted to visit the King of Spain, who was exiled in Switzerland.
In that campaign, the competition featured 16 sides, but only seven were national champions. And Real claimed the trophy by beating Stade de Reims in the final.
The competition then grew to 22, 24 and later 26 teams in the following seasons, but as defending champions, Madrid went straight into the last 16 while others had to play preliminary rounds.
Nevertheless, Los Blancos almost went out in their first tie in 1956-57, beating Rapid Vienna 4-2 at home, before losing the second leg 3-1 in Austria. Fortunately for them, the away-goals rule did not exist then (it would have knocked the Spanish side out) and instead, a third game was played.
The match went ahead in Madrid and it is claimed that Real paid a significant sum to bring the Austrian side back to the Bernabeu for the decider, which was won 2-0 by the Spanish side. Without that win, Los Blancos would not have been able to triumph in the next four competitions because they won La Liga just twice between 1956 and 1960 – and only the champions qualified back then.
But they did and the rest is history. Real won five European Cups before anybody else had even won one and now, they have exactly five more than the competition's second-most successful side, AC Milan, with seven.
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Their first European Cup (now the Champions League) "in colour" would arrive in 1998, yet that too was controversial as Predrag Mijatovic's winner in a 1-0 victory over Juventus should have been ruled offside.
Obviously, there was more contention against Juve again in the quarter-finals of this season's competition and here is a closer look at some of the controversial calls that many believe have helped Real in Europe over the past few seasons...
Bale foul on Juanfran before Sergio Ramos' late leveller
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Atletico were seconds away from winning the Champions League in Lisbon after Diego Godin's early goal gave Diego Simeone's side a lead they held on to until the third minute of added time. Sergio Ramos time.
The story is well known now. Luka Modric curled in a corner and the defender rose to head home a dramatic late leveller and force extra time. Atleti, having defended so bravely and played Barcelona at Camp Nou just days earlier to claim La Liga, were dead on their feet and Real won 4-1 in the end.
But a closer look shows Gareth Bale's elbow outstretched in Juanfan's face at the precise moment Ramos rises to head home. Was it a foul? Atletico certainly think so.
Ramos' offside goal in Milan
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Two years later, Sergio Ramos did it again. In a repeat of the 2014 final, Real met Atleti in Milan and this time, Los Blancos won on penalties after the two teams played out a hard-fought 1-1 draw at San Siro.
The Madrid captain opened the scoring after a quarter of an hour, before Yannick Carrasco levelled with 11 minutes left. However, replays showed that the Spain defender's effort should have been ruled out for offside.
Asked about the use of VAR (video assistant referee) last December, Ramos said: "You can't win a match with an offside goal." Essentially, though, his strike against Atleti not only won a match, but also the Champions League – and rival fans on social media were quick to point that out at the time.
More controversy as Real beat Bayern
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Real Madrid went on to retain their title in 2016-17 by beating Juventus 4-1 in the final. There was nothing controversial about that, but the same cannot be said about their tie against Bayern Munich in the quarter-finals.
Zinedine's Zidane's side were on the ropes as Bayern stormed back to overturn a 2-1 first-leg deficit and force extra-time at the Santiago Bernabeu. However, Los Blancos netted three times in the additional 30 minutes to advance with a 6-3 aggregate win.
However, Arturo Vidal was sent off in controversial circumstances (his second booking was not even a foul), while Casemiro probably should have seen red and Cristiano Ronaldo scored two offside goals.
Closer analysis showed that Bayern's second (a Sergio Ramos own goal) should also have been called offside, while the Germans were awarded a ridiculous penalty in the first leg (which they missed) and Vidal could have been dismissed earlier for a bad foul.
Nevertheless, that did not stop the German giants talking about "robbery". "The referee put us out," Vidal said. And coach Carlo Ancelotti added: "It was an injustice and the whole world saw it."
Buffon's red rage after questionable penalty call
CURTO DE LA TORRE
It was a get-out-of-jail-free card for Real Madrid. After throwing away their three-goal lead from the first leg against Juventus in the quarter-finals earlier this month, Los Blancos were awarded a penalty deep into stoppage time as Medhi Benatia was adjudged to have pushed Lucas Vazquez in the area.
Juve goalkeeper Gianluigi Buffon was sent off for his furious protests at referee Michael Oliver and raged against the official afterwards. "A human being cannot destroy dreams like that at the end of an extraordinary comeback," he said. "Clearly you cannot have a heart in your chest, but a bin."
And later, he added: "You have to be a murderer to make the last two decisions the referee made." Meanwhile, Barcelona-based newspaper Sport opened their edition the following day with the headline "The robbery of the century".
Whether you believe it to be a penalty of not, that was a complete exaggeration and Madrid's players and also Zidane later complained of an "anti-Real" agenda. In the eyes of many, however, they had received a helping hand once again.