Denis Law, christened the 'King of Old Trafford' after scoring 236 goals in 11 years after joining Manchester United in 1962, also played his part in sending his former club down to the Second Division when he backheeled the winner for rivals Manchester City in the penultimate game of the season in 1974. While United would have been relegated even if they have drawn the game, Law's goal has gone down as one of the most memorable in history and, crushingly, proved to be his final touch in English football.
Footballing dynasties are built and, with time, invariably tumble, and the early 1970s saw even the great Manchester United fall into decline. With manager Sir Matt Busby moved upstairs to a role on the board in 1969 and the retirement of Bobby Charlton four years later, the side were in a period of transition that also saw the high-profile exit of the legendary George Best at the tender age of 27 in 1974.
Unable to cope with the level of expectation at Old Trafford, Busby's two successors, Wilf McGuiness and Frank O'Farrell, had both lasted less than a year and even a brief return by the great man himself could not lift the side beyond eighth in the league. Indeed, the tenure of Tommy Docherty, in late 1972, began as a salvage job as they were staring relegation in the face; he had been recommended for the role by striker Denis Law, who had worked with him in the Scottish national side.
Docherty, arriving in December, managed to retain their place in the top flight by turning around the club's form in the second half of the season, but the new boss did not repay Law's faith in him.
Law's decline had also begun as the decade ticked over. Injury concerns had begun to hinder his ability to play first-team football and he had been transfer listed for around £60,000 in the spring of 1970, but no suitors had made themselves known. A blistering start to the following season had suggested that Law was not done just yet but, when his knee injury reappeared, Docherty decided that he was not worth keeping on the books (saying he was just ''going through the motions'') and let him join rivals City on a free transfer ahead of the 1973-74 season.
Any hopes the United fans had that Docherty would continue his good start faded quickly as seven defeats in the first 12 matches saw them plummet once more. Without Law leading the line, United struggled for goals and, by Christmas, the situation was such that one of the team's leading scorers - with two penalties - was goalkeeper Alex Stepney.
Away from their league woes, there was no solace either as United were knocked out of the League Cup by October, losing at home to Middlesbrough, and out of the FA Cup by January after a home defeat to Ipswich Town.
A brief revival occurred in April when they beat fellow strugglers Norwich and also Newcastle and Everton, but it proved only a flash in the pan and a 1-1 draw at Southampton and 1-0 defeat at Goodison Park saw them needing all three points from the visit of mid-table City in the penultimate game of the season and also a helping hand from Norwich to beat Birmingham.
The first Manchester derby of the 1973-74 season had been a feisty affair at Maine Road as both Mike Doyle and Lou Macari were involved in a spat that saw them sent off. The pair had failed to leave the pitch after their dismissals, causing referee Clive 'The Book' Thomas to lead all the players back into the dressing room, and the police were even called to keep Doyle and Macari in place while the game restarted. The match ended in a dour 0-0 draw, but by the time that the second derby fixture came about in April, all the attention had turned to Law, who was returning to Old Trafford for the first time.
Law's appearance in the blue of City saw no bitterness from the United fans though. Having ''elected him to their exclusive monarchy'', according to The Guardian's Eric Todd, the second largest crowd of the season gave him a ''generous encore'' and ''cheered him again when he trotted up for the toss of the coin''.
Despite what was at stake and the events of Maine Road a few months earlier, the match itself was surprisingly uninspired. United, with more to lose, dominated the attacks but were unable to break through the City defence and were left frustrated as both Willie Donachie and Colin Barrett cleared off the line.
After a goalless 82 minutes, Francis Lee played the ball towards Law, who was standing with his back to goal. The Scotsman instinctively back-heeled the ball through the legs of goalkeeper Alex Stepney into the net, but remained motionless as the City fans cheered. Historian David Goldblatt remembers: ''Law, his arms frozen by his side, rigid and unemotive, was mobbed by his new team-mates.''
The United legend had helped condemn his former side to defeat and, in turn, relegation from the First Division for the first time in 37 years, although Birmingham's win over Norwich meant it would have happened anyway. Later, Law said: "I have seldom felt so depressed in my life as I did that weekend. After 19 years of giving everything I had to score goals, I have finally scored one which I almost wished I hadn't."
Todd wrote in his Guardian report that: ''Saturday's greatest irony at Old Trafford was, without doubt or exception, Denis Law's goal. It was 'the most unkindest cut of all' in the words of Marcus Antonious - he was not in the press box of course - who in the same speech said: 'If you have tears, prepare to shed them now.' Which seemed no less relevant.''
Law, dishevelled and obviously distressed, was immediately substituted and never played league football again, but his career ended on an even more sour note as hundreds of United fans invaded the pitch in the hope that the game would be abandoned. The Daily Mirror's Frank McGhee wrote in the strongest terms possible of the hooligans, maintaining that ''they are a cancer that needs cutting out'' and advocating that the entire Stretford End be closed off for the next season.
The pitch invasion got its intended outcome - the first match in English football to be stopped after crowd disorder - but United were a Second Division side as the league decided the result should stand. McGhee felt there was a contrast between the hooligans and their former hero.
''They [the invading fans] have no love for the game, otherwise their reaction at the relegation of their team would have mirrored the reaction of the man who relegated them, Dennis Law,'' he wrote. ''Quite simply, that was sadness. I have seldom seen a more poignant moment in sport captured on television than the expression on Law's face after he had scored the goal that sealed his old side's tomb. And I have never seen anyone having to be consoled rather than congratulated for scoring. All his life, Denis has loved goals. That one, even though it was a bit special, he hated.''
What happened next? United, already knowing their fate, lost their final game of the season away at Stoke. The former kings of Europe were no longer even the kings of Manchester, although Docherty retained the confidence of Busby and the board and led them back into the top flight at the first attempt. It would not be long before they were back on top of the English game but, for Law, his backheel was his final touch of a ball in England as he retired after the 1974 World Cup with Scotland. Even though the goal actually made no difference to United's plight, the Scot has never been able to escape the moment and told the Daily Mail in 2010: ''I was inconsolable. I didn't want it to happen. How long did the feeling last? How long ago was the game? Thirty-odd years. There is your answer.''