LONDON (AP) -- It's been the season of the underdog in the FA Cup, yet the presence of England's four Champions League entrants gives the famous competition an ominous look heading into the fifth round this weekend.
Only seven Premier League teams made it out of a shock-filled fourth round last month, but the survivors include Manchester United, Manchester City, Arsenal and -- only just -- Chelsea.
The European champions were forced into a replay against third-tier club Brentford on Sunday to confirm their place in the fifth round, while the other big three were given favorable home matches in the draw for the last 16.
There could still be room for surprises, however, with Luton bidding to become the first non-league club in 99 years to reach the quarterfinals when it takes on second-tier club Millwall at Kenilworth Road.
And third-tier team Oldham -- conqueror of Liverpool in the last round -- looks to bring down another giant from Merseyside when Everton, which is fifth in the Premier League, visits Boundary Park.
The exploits of Luton and Oldham, who have fallen on hard times since being relegated from the Premier League in the 1990s, has given the FA Cup a major shot in the arm. It ensured the world's oldest knockout competition remained in the spotlight in the season its rival, the League Cup, has taken center stage with fourth-tier club Bradford's shock run to the final at Wembley Stadium, which takes place on Feb. 24.
Luton has been the biggest so-called "giant-killer," eliminating Norwich 1-0 in the fourth round to become the first non-league side to beat a topflight team in the FA Cup since 1989.
Only six other teams from outside England's Football League have made it this far in the competition since World War II.
"It's such a buzz," Luton captain Ronnie Henry said. "When you're young, you dream of winning the FA Cup. Who knows?"
Standing in their way now is Millwall, a match which brings back memories of an unsavoury meeting between the two teams in the FA Cup in 1985 -- at the height of English football's era of hooliganism.
On that occasion, which has subsequently been dubbed the "Kenilworth Road Riot," Millwall fans went onto the pitch after the final whistle and threw chairs at police officers. A total of 47 people, including 33 police officers, were injured and 31 people were arrested and Luton reacted by banning away supporters from its ground for four years.
"I think we've moved on as a society, let alone moved on in football," Luton chief executive Gary Sweet said.
Luton is currently seventh in the Conference Premier, the fifth tier of English football.
Everton is determined not to slip to the same fate that befell Liverpool, which appeared to underestimate the threat posed by a fired-up Oldham last month.
"You know you're going to be playing in difficult conditions and sometimes things don't go for you," Everton defender Leighton Baines said, "but we've just got to go there and be professional.
"You've got to make the right decisions and not get caught up in the different style of play which they'll try and force on the game. We need to play our own game and if we can get the first goal, then that can make a big difference."
Oldham bizarrely fired its manager, Paul Dickov, soon after the win over Liverpool because of the team's poor run of form in the league.
Also Saturday, Arsenal hosts Blackburn and will be looking to stay in the hunt for its last realistic hope of silverware this season.
Arsene Wenger's side, without a trophy since 2005, is still in the Champions League but is one of the outsiders, especially since it faces Bayern Munich in the last 16.
Third-tier cluv MK Dons hosts second-tier team Barnsley in Saturday's other game.
On Sunday, Man City is at home to Leeds, which beat Tottenham in the fourth round, and Wigan visits Huddersfield, which plays in the second-tier League Championship.
The only all-Premier League match sees Man United host Reading on Monday.