The most recent competitive meeting between the Bees and the Blues was 63 years ago, when Chelsea claimed a 1-0 FA Cup third-round in front of 38,000 fans.
Griffin Park could hold its largest crowd in 30 years if it is full to its 12,000 capacity tomorrow, with few anticipating an upset as Chelsea seek to defend the FA Cup in a season where opportunities for silverware are dwindling.
"They will take the game seriously," Rosler said.
"They can only win the FA Cup and the Europa League and a club like Chelsea has to win trophies each year.
"Chelsea will still have an extremely strong team. I still think their players will underestimate us. It's a human reaction.
"I was as a player the same and I think that is our chance.
"We have to believe in our chance and we have to go for it."
Chelsea lost the two-legged Capital One Cup semi-final to Swansea, who meet League Two Bradford in the Wembley final.
Brentford eliminated Bradford from the FA Cup in the second round as part of their eventful run in the competition thus far.
The Bees beat non-League Borehamwood in the first round, required a replay to advance at the expense of Bradford and another replay, which again took place at Griffin Park, to beat Southend and go through to the glamour tie with the holders.
Rosler is confident his side have players who can trouble Rafael Benitez's Chelsea.
Clayton Donaldson has scored four goals in the competition to date - finding the net in each round - while Harry Forrester is a tricky player.
"We have players who can cause any opposition problems, especially when it's a one-off game," Rosler added.
"We have pace, we have technically good players and we are a fit team. We can work very hard against the ball, pressurising and hopefully we can show that on Sunday."
In the moments before kick-off, former Manchester City striker Rosler will urge his players not to be overawed by the occasion, but to seize the opportunity.
He said: "Go out, enjoy it, but don't get carried away by the occasion. Focus on the job in hand.
"Test yourself. Relish the chance to compete and make the most of it.
"My job is to instruct, motivate and inspire my players for a fantastic opportunity on Sunday.
"I'll be excited like my players. We've been working very hard to come to a stage when we can compete against the European holders, against a top Premiership side full of world stars. The bench is full of top stars. We just want to make the most out of it.
"For everybody involved. For players, backroom staff, coaching staff and also the manager. We're a unit here in this club.
"We're going very much in one direction. We want to impress. We want people to take notice of Brentford."
