Sunday's semi-final against Tottenham has been billed as the least important of the Blues' season-defining matches during their punishing end to the campaign.
But the Wembley showpiece is far from expendable, according to caretaker manager Di Matteo, who vowed to play his strongest team and order them to hold nothing back this weekend.
"Whatever it takes for us to reach the final, we will do," he said.
"We're not going to throw anything away, absolutely not."
If that meant extra-time and penalties three days before Wednesday night's Champions League semi-final first leg against Barcelona and six before next Saturday's crunch Barclays Premier League trip to Arsenal, so be it.
Di Matteo added: "This is a massive game for the players, the team and for the club, and for our supporters. A big, big game for us.
"Nobody will have Barcelona at the back of their minds. We are going to be focused on the FA Cup on Sunday, to try and reach the final."
That also meant being prepared to risk captain John Terry and left-back Ashley Cole, despite the former's broken ribs still healing and the latter having only just returned to training after an ankle injury.
Di Matteo said: "Every game brings problems with knocks, injuries and recovery times. Every player recovers differently."
Winning on Sunday would increase Chelsea's fixture headache, ensuring they would play every midweek and weekend until the end of the league season on May 13.
Di Matteo said: "It'll be a very welcome problem - seriously. We want to win and are looking forward to the game.
"We are going to play it at the best of our ability and strength."
Di Matteo's bullishness was in contrast to his bitter complaints last week about Chelsea being forced to play at 6pm on a Sunday just days before they meet Barca.
He called for an overhaul to the fixture calendar, saying: "English teams don't get an advantage when they're involved in Europe.
"There should be a review so that those involved in Europe get better fixture dates."
Chelsea are underdogs to achieve any of their aims this season, whether it be a top-four finish, Champions League glory or their fourth FA Cup triumph in six years.
But Di Matteo has never lost to Tottenham either as a player or manager, while his squad boasts far more trophy-winning and Wembley experience than their opponents.
"It won't be a nervous game because they've been involved in so many semis and finals," he said.
Despite having trailed Spurs in the league for almost the whole season, Chelsea arrive at Wembley in better form, winning eight and losing just one of their 11 matches under Di Matteo.
Tottenham, meanwhile, have won only one of their last eight league games and Di Matteo said of their slump: "It's welcomed by us.
"We made up a lot of points on Spurs, and will continue to try and do that so we can finish above them at the end of the season."
Speculation over Harry Redknapp becoming England manager has been blamed by some for Tottenham's recent run.
This has been rubbished by Redknapp, who recently claimed his players do not care whether he will be in charge next season.
Di Matteo said: "Maybe some do care, some others don't.
"Generally, they're professional and do a job with the manager who has been appointed by the club."
Redknapp is undoubtedly auditioning for the England job and Di Matteo - who many believe is in a similar position regarding the current vacancy at Chelsea - added of his opposite number: "He's a great manager. He's been in the football industry for so many years, and has built a nice team at Spurs.
"He looks like he's going to be the new England manager and I think he fully deserves the chance to be able to lead his country."
Asked whether his own England players would back Redknapp's appointment, Di Matteo added: "A lot of them know him very well and I think the general consensus is that the players, in general, all like him."