There have been so many controversial decisions made by referees in football history.
But what is the worst mistake a referee has ever made?
Goal asked their followers on Twitter to name the worst decisions they've ever seen.
Thousands of fans got involved and you can view some of the most popular answers below...
Thierry Henry's handball | France vs Ireland | 2009
France and Ireland were in extra-time of their match, with a 2010 World Cup spot the prize for the winner.
It was France who booked their place in South Africa after they scored one of the most controversial winners ever.
Thierry Henry blatantly handled the ball and set up William Gallas to score the winner. Despite Ireland's heavy protests, the goal was allowed to stand.
Arturo Vidal's red card | Real Madrid vs Bayern Munich | 2017
In the second leg, with the tie finely poised at 3-3, Vidal was given a second yellow card after a perfectly timed slide challenge on Marco Asensio.
Real scored three times in extra-time to cruise through to the semi-finals.
Raheem Sterling's penalty | Man City vs Shakhtar | 2018
Sterling was somehow given a penalty after he kicked the ground. No one was anywhere near him.
Fortunately, the decision didn't affect the end result too much as City romped to a 6-0 victory.
Jan Vertonghen's goal disallowed | Tottenham vs Sunderland | 2015
Vertonghen's late goal was ruled out for offside, despite the fact he was miles inside his own half.
Fortunately for Spurs, the decision wasn't costly as they held on for a 2-1 victory.
Roy Carroll's blunder | Tottenham vs Man United | 2005
With the game goalless and time fast running out, Pedro Mendes tried a speculative effort from the half-way line.
Roy Carroll was well placed to easily gather the ball but he failed to gather. The ball went well over the line but a goal was not given.
Nani's red card | Manchester United vs Real Madrid | 2013
Man United were leading 2-1 on aggregate against Real Madrid in the last-16 of the Champions League in 2013.
But, in the 56th minute, Nani was controversially sent off after his high boot caught Alvaro Arbeloa.
Real made their advantage count as they scored twice to book their place in the quarter-finals.
Robin van Persie's red card | Barcelona vs Arsenal | 2011
One of the most controversial decisions in red card history.
Arsenal were leading Barcelona 3-2 on aggregate in their Champions League last-16 tie in 2011.
It all fell apart for the Gunners when Van Persie was controversially sent off.
The Dutchman was sent through on goal in the 55th minute only for the whistle to blow for offside.
Van Persie did not hear and, just moments after the whistle blew, he had a shot on goal.
He was consequently given a second yellow card for time-wasting. Arsenal could not hold on as they conceded twice in the final 25 minutes to enter the competition.
Frank Lampard's no goal | England vs Germany | 2010
But, despite England's protests, the goal was not given.
The Three Lions would go on to succumb to a 4-1 defeat but the scoreline could have been very different had Lampard's goal stood.
Kieran Gibbs red card | Chelsea vs Arsenal | 2013
Andre Marriner gave Chelsea a penalty when Alex Oxlade-Chamberlain handled the ball on the line.
In a case of mistake in identity, the referee then showed Kieran Gibbs a straight red card.
Oxlade-Chamberlain confessed that he was the one who should have been sent off but Marriner did not listen.
Tom Henning Ovrebo's performance | Chelsea vs Barcelona | 2009
Chelsea thought they should have had four penalties in their Champions League semi-final clash against Barcelona, but none were given.
Andres Iniesta then struck late on to book Barcelona's place in the final and send Chelsea crashing out.
Didier Drogba absolutely lost it at full-time.
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