After securing a 1-0 advantage in last week's first leg encounter at Estadio da Luz in Lisbon, the Blues go into Wednesday's clash as favourites to progress to the semi-finals, but the Brazilian is adamant that nobody in the dressing room is taking anything for granted.
"It will certainly be a difficult game," Ramires told the club's official website. "We have an important advantage from the first game, obviously, but we have 90 tough minutes in front of us and we are going to face a serious challenge tomorrow.
"When facing Benfica you know they will come out motivated and do everything to win. Despite the disadvantage from the first game I am sure they will do everything to stop us.
He added: "I have never previously had an opportunity to play against a team I played for before. It was a strange feeling last week and the Benfica fans showed a lot of affection during the last game.
"Today though I am a Chelsea player and I hope tomorrow I can do everything I can to help Chelsea beat Benfica."
After Barcelona confirmed their place in the last-four for the fifth consecutive season with a 3-1 victory over AC Milan at the Camp Nou last night, Roberto Di Matteo's players have the incentive of testing themselves against the competition holders if they progress to the semi-finals.
However, Ramires insists he is not looking that far ahead, as concentration remains firmly on Benfica, who will provide a stern test of their European credentials.
"There is a lot of talk already about Barcelona but we as players don't look that far ahead," the 25-year-old continued. "We are concentrating on every single game as it comes.
"We respect Benfica a great deal, it is a massive club with a lot of tradition so there will be no talk of Barcelona. I am sure there will be plenty of talk afterwards if we progress but for now the focus is solely on this game."