Cardiff's Millennium Stadium hosts its fourth FA Cup Final on Saturday as mighty Manchester United face Millwall.
Sir Alex Ferguson's Red Devils start as 1-10 favourites in their first final since sitting out the 2000 competition to play in the World Club Cup.
And Millwall, who are sweating on the fitness of player-manager Dennis Wise, have been written off by many pundits.
But they will be hoping to spring a Cup shock in front of 72,500 fans on one of British sport's biggest occasions.
On paper, the Lions have little chance against the Old Trafford all-stars, including Ryan Giggs, Paul Scholes and fit-again talismen Roy Keane and Ruud van Nistelrooy.
But second-tier sides have pulled off huge upsets in the past, as when Southampton toppled United in the 1976 final.
And Millwall chairman Theo Paphitis believes a fairytale ending is on the cards.
"It is a great, great opportunity for us as an FA Cup Final is something that dreams are made of," he said.
His team's task will not be easy however.
Following Manchester United's much-criticised absence in 2000, Ferguson has warmed to the competition and this year's finale is his last chance to end a barren season.
"We've not been in a final for five years and I think we've served our penance for not going," Ferguson said after the 1-0 semi-final win over Arsenal.
Whatever the result, the Cup Final has traditionally been a big day out for fans and police have stepped up security in a bid to ensure that nothing spoils the occasion.
Armed officers will carry out random checks on lorries coming into Cardiff before the game.
"In those checks we'll be looking for vehicles that fit a certain profile - vehicles carrying petroleum, chemicals - large-sided vehicles that could hide something," said Stephen Cahill, assistant chief constable of South Wales Police.