Saturday 14 March 1964.
West Ham United face holders Manchester United at Hillsborough in their first FA Cup semi-final in 31 years.
Just seven days previously, the Hammers had fallen 2-0 to the Red Devils in a Division One fixture at the Boleyn Ground, despite the visitors leaving out their three best attacking players, Bobby Charlton, George Best and Denis Law.
Charlton, Best and Law are all in the starting XI at Hillsbrough where, to make matters worse, the conditions are atrocious, with heavy rain turning the pitch into a muddy bog.
On the morning of the game, The Times newspaper asks 'Who can now turn away from Manchester United?', who have the 'mark of champions' and are the 'modern giants of the competition'.
Tellingly, the preview concludes 'If West Ham win today, they will deserve the cup'.
Forty-eight hours later, the same newspaper's Monday headline screams 'Moore carries West Ham to Wembley'.
West Ham have upset the odds - and the terrible playing surface - to reach just the second FA Cup final in their history, 41 years after their first.
For those old enough to remember, many of whom made the tortuous, rain-swept journey to Sheffield to watch the game in person, Saturday 14 March 1964 is a day they will never forget.
'Moore's Muddy Marvels', as another newspaper headline labelled the Hammers, had blunted the triple threat of England midfielder Charlton, 17-year-old Northern Ireland winger Best and Scotland centre forward Law, with the England captain leading the way with a 'flawless' display.
Football writer Tom Holley summed up Moore's performance as follows: "Moore turned in a game I have rarely seen equalled. He was flawless. He was the mainspring of the defence, yet still set his attack on the move with long, accurate passes."
At one stage, the exhausted skipper collapsed on the turf in agony, the sapping surface causing him to suffer cramp in his legs, but Moore - and his West Ham team - would not be denied.
The triumphant 1964 FA Cup semi-final team
Early on, West Ham rode their luck as Best waded through the quagmire before unleashing a shot that cannoned back off Jim Standen's crossbar.
The first half ended scoreless, but it would take just ten minutes of the second half before the Londoners took a lead they would never relinquish.
Manchester United goalkeeper Dave Gaskell launched the ball upfield into the gloom, where it was met by the head of West Ham centre-half Ken Brown. The ball bounced and was lobbed over Gaskell by midfielder Ronnie Boyce from fully 25 yards.
Afterwards, West Ham's players claimed this had been their plan all along, as they had seen that Gaskell liked to stray far from his goal line during a special scouting mission to Manchester United's sixth-round victory over Sunderland earlier that week.
Seven minutes later, Boyce beat Gaskell again, glancing a header into the net after John Sissons had found full-back Jack Burkett with a short corner.
With less than half-an-hour to play, the Hammers were within touching distance of their first FA Cup final since the 'White Horse' final of 1923 - the first played at Wembley.
However, Ron Greenwood's team would not advance without having to withstand a few body blows - literal and figurative - from Matt Busby's star-studded side.
First, goalkeeper Standen was left groggy and blinded by a face full of mud following a challenge with 13 minutes to go.
Winger Sissons raced to the touchline for a bucket of water to both wash and revive the stopper.
With his sight still not clear, Standen refused assistance from the trainer standing by his goal because he did not want anyone to think West Ham were time-wasting - how times change!
Within a minute, though, Standen was punished for his heroism as Phil Chisnall crossed and the blond head of Law nodded the ball into the net.
West Ham's lead, which had looked comfortable moments before, was now a slender one.
While some players would have panicked as their Wembley dream looked poised to turn into a muddy nightmare, Moore's calmness was there for all to see.
Instead of clearing the ball high into the Hillsborough stands, the great defender glided through the swamp, beating three challenges before arching a majestic pass through to Geoff Hurst.
The future World Cup final hero, then just 22, showed all the self-assurance of a veteran to calmly slot past Gaskell and put the game beyond Busby's men.
Moments later, the final whistle was blown and some West Ham's players - their sky blue and claret hooped kits caked in mud - raised their arms in celebration. Others were simply too tired to do so, trudging slowly, off the pitch, albeit with broad smiles on their faces.
Afterwards, the great Manchester United manager Busby, who had already led his side to three Division One titles and two FA Cup successes and would lift the European Cup in 1968, was magnanimous in defeat.
"The better side on the day won and West Ham deserve to go to Wembley," said Busby. "Conditions were bad, but we have no excuses."
For the Hammers, it was a case of a job perfectly done, but with a final date with Division Two Preston North End to look forward too, manager Greenwood was not yet content.
"Pleased? Of course I am pleased," the great tactician told newspaper reporter Ken Jones, "I'm always pleased when we have the right application and the right amount of effort.
"But remember, we have still got to win the Cup! We have only reached Wembley. We haven't won there yet."
Bobby Moore grimaces after suffering cramp on the muddy pitch
While Greenwood was already planning for his first Wembley final as West Ham manager, his players enjoyed a celebratory train journey back to London.
Joining them were reporters from many of the newspapers. Back then, it was their achievement rather than their enjoyment of a glass or two of Champagne which made the headlines.
It was during that happy train ride that captain Moore spoke to journalists, revealing that the Hammers' game-plan had worked perfectly.
"We noticed that their goalkeeper had the habit of straying off his line - that's why Ronnie went for a lobbed goal," said the great No6.
"We also noticed that their centre-half Bill Foulkes played tightly on his centre forward - that's why I was looking for Geoff Hurst to make the run through the middle for the third goal.
"More than anything, we noticed that United only produced their magic when they got on top. We knew that if we all played our parts, we could beat them. We had faith in ourselves."
Seven weeks later, on Saturday 2 May 1964, the same eleven players would stride out proudly behind Greenwood at Wembley, the Home of Football, for their final date with Preston North End.
Every West Ham fan knows what happened that day, and we will relive it all over again in the Official Programme for the visit of Tottenham Hotspur on 3 May 2014.