The match does not start until 8pm but Three Lions supporters were getting into the party spirit hours earlier.
By lunchtime some had already arrived at Wembley, northwest London, to soak up the atmosphere.
Others were filling up pubs and big screen parks up and down the country, as the team puts in some final prep before taking to the field.
England superfan Chris Dowse, who lives on the flag-bestrewn Kirby Estate in Bermondsey, south-east London, said he had declined the offer of tickets to the match semi-final because he would rather watch the game in the company of his neighbours.
The 42-year-old told the PA news agency: “I’ve been offered tickets but I’ve turned them down. Firstly, I’m not rich and I’d like to spend that money on my kids.
“But secondly, I am really proud of what we’ve achieved on this estate, so I will be watching it here.”
Victory will see England in their first major final since the 1966 World Cup.
Italy await the winners of the match following a semi-final victory against Spain on Tuesday in which they triumphed on penalties when the game ended in a 1-1 draw.
After a slow but steady start, England side came to life in the last game against Ukraine in Rome.
In a 4-0 win, the captain and Tottenham striker Harry Kane bagged a brace, while Liverpool’s Jordan Henderson and Man United’s Harry Maguire also chipped in with goals.
Before that, there were tight but professional wins against Croatia and the Czechs, and a historic victory against Germany at Wembley.
An underwhelming draw with Scotland in the group stage has been the only disappointment to date.
Should England win against Denmark there are likely to be jubilant scenes witnessed across the country.
Fans watching the game at watering holes are expected to buy more than 50,000 pints of beer per minute, an industry body estimates.
The British Beer and Pub Association predicts punters will purchase some 6.8 million pints over two hours.
The BBPA estimated that overall, almost 10 million pints would be sold on Wednesday.
That figure would be closer to 12 million were coronavirus restrictions such as social distancing not in place, the group claimed.
Emma McClarkin, BBPA’s chief executive, said: “With England fans’ support, we hope that pubs will sell 6.8 million pints during the semi-final match.
“If the team goes on to win, a final at Wembley awaits, which would be a huge boost to our pubs and the nation.
“After a long wait, the pubs we love should be restriction-free from 19 July. Only when the restrictions are removed can our pubs recover, but to do so they need government investment to build back better.”
It came as Downing Street announced plans to extend pub opening hours by 15 minutes on Sunday evening, to cater for the potential for extra time and penalties in the Euro 2020 finals.
On Wednesday Boris Johnson was among those urging the England team on, saying: “Gareth Southgate and the England squad have done the nation proud in the Euros, and tonight we will all be wishing them the best of luck in getting to the final. Bring it home!”
Labour leader Sir Keir Starmer also had words of encouragement for the team, saying: “Gareth Southgate and the squad will have the whole nation behind them tonight. Both on and off the pitch, they have shown the best of England. There’s been only one song featured in our house since Saturday – It’s Coming Home.”
Those watching from outside venues may need to be prepared for all weathers, with sunshine and showers forecast for parts of England throughout the day, although London is expected to remain dry during the match.
Additional reporting by Press Association