Manchester United against Liverpool is one of football's most intense rivalries but few have been as controversial as Good Friday 1915, when one of British sport's worst betting scandals took place.
Manchester United against Liverpool is a match which rarely fails to deliver some element of controversy. But the recent Steven Gerrard 38-second red card has nothing on the tie between the clubs 100 years ago.
On that day, there were "two matches going on at once" during a crucial bottom of the table clash at Old Trafford.
After an approach by a third party, some players from both sides hatched a plot to rig the game for a 2-0 home win, which eventually saw United avoid relegation.
"There was the realistic possibility of relegation for both of the sides - so it was an important match," says Graham Sharpe, a sports writer who has researched the fixture.
"It was overshadowed by the First World War, which had been raging for several months, and you could make the case that those players thought to themselves, 'when this season has finished, there may not be one to follow'."
Many footballers had already signed up to fight, while others played on.
There were rumours about the honesty of the tie, even before kick-off.
There were eyewitness accounts of the two sets of players meeting up in Manchester pubs to discuss the outcome, before bets were placed at up to 8/1.
Bookmakers were naturally suspicious if they saw "significant amounts of bets" on one particular outcome or score, Mr Sharpe says.
A crowd of up to 18,000 witnessed one of the fixture's most extraordinary passages, when United were 1-0 up and won a penalty.
Patrick O'Connell, a centre half and the side's captain, stepped up and hit it so far wide it nearly hit the corner flag, according to match reports.
Mr Sharpe explains: "From all reports, he walked back up the pitch laughing as he thought 'well it doesn't matter, we can get another goal whenever we want one'."
There are accounts of a dressing room row at half-time, with some players who were not in on the plot threatening not to come out for the second half.
And after United got a second goal, the bet was nearly ruined when Liverpool forward Fred Pagnam hit the crossbar.
"A number of his teammates gestured angrily towards him," Mr Sharpe says.
Other major sporting fix incidents
Baseball's 1919 Black Sox scandal - "Say it ain't so, Joe," was the apocryphal cry of the heartbroken kid who could not believe his hero, "Shoeless" Joe Jackson, could have done such a dastardly thing as throw the 1919 World Series.
But it was true, and the United States was rocked by the news that several members of the Chicago White Sox had conspired to fix the outcome of games against the Cincinnati Reds in return for $100,000 ($1.42m /£960k in today's money). Several of their players, including Jackson, were given life bans.
Pakistan 2010 cricket spot-fixing scandal - Former Pakistan cricket captain Salman Butt was jailed for 30 months in 2011 for his part in a conspiracy to bowl deliberate no-balls in a 2010 Test match against England.
Former world number two Test bowler Mohammad Asif was jailed for one year and 19-year-old bowler Mohammad Amir was given six months.
Sheffield Wednesday 1964 betting scandal - Former Sheffield Wednesday centre half Peter Swan and his fellow player David Layne bet £50 that Ipswich Town would beat their own team Sheffield Wednesday 2-0.
They were jailed for four years for "conspiracy to defraud". Swan's eight year ban cost him his place in the 1966 World Cup as he had been a regular in the England team.
Failed floodlights scam 1997 - A businessman, with links to Chinese Triad gangs, was convicted of taking part in an Asian betting scam by plotting to black out a Charlton Athletic v Liverpool game.
Two previous matches - West Ham united v Crystal Palace and Wimbledon v Arsenal - saw the floodlights fail when the scores were level, a result favourable to a Far East betting syndicate.
"It's almost as if there were two matches going on at once."
Suspicions were raised almost immediately after the game, with an inquiry announced shortly afterwards.
Later that year, Liverpool players Tom Fairfoul, Tom Miller, Bob Purcell and Jackie Sheldon and United's Enoch West, Sandy Turnbull and Arthur Whalley received lifetime bans.
Lawrence Cook, of Chester, and Manchester City's Fred Howard were also banned for their parts in the scam.
The Football Association said the players had "sought to undermine the whole fabric of the game and discredit its honesty and fairness."
Players were then called up to fight in the war.
When they returned, many had their bans lifted in recognition of their war efforts, while Turnbull received a posthumous pardon as he was fatally wounded at Arras in 1917.
However, Enoch 'Knocker' West, who had refused to admit his role in the plot and even sued the FA for libel, was not pardoned and remained banned from football for 30 years.
A recent campaign to clear his name has stalled because the FA said his documents were lost.
Alex Jackson, Collections Officer at the National Football Museum, thinks the players' motivations for the plot could be similar to that of the US baseball players involved in the 1919 Black Sox scandal.
He said footballers' wages had fallen after the outbreak of war and - similar to the Chicago White Sox players - financial reward was the aim.
Mr Sharpe believes it was "a combination of 'let's stick two fingers up to authority' and 'let's cover ourselves in the event of losing our livelihoods or in fact our lives".
Mr Jackson said: "It was probably the biggest scandal of the time as it involved quite a number of players and two of the biggest clubs in the league.
"It is interesting that the players were approached by a third party to arrange the scam, but they were never found out".
Mr Sharpe said the match changed the way the British betting industry operated.
"It was the first major case of its type and will have made the authorities wary of this sort of behaviour. For that reason, it will never be completely forgotten."