The current holders of that particular trophy, and with four successes to their name in the last six years, the Blues edged out Manchester United 1-0 on Easter Monday to make the last four.
Both sides struggled to produce their best at Stamford Bridge, with tired legs starting to take their toll, but one moment of brilliance from Demba Ba allowed Chelsea to dash United's double dreams.
Benitez, who has faced widespread criticism during his time as the Blues' interim boss and was looking for a positive response to Saturday's disappointing 2-1 reversal at Southampton, told the club's official website afterwards: "It was very important for everyone to win. If not we're out.
"We worked so hard at Old Trafford and had chances to win the game, and in the end deserved to win. This was a great game and a great victory for us.
"I am really pleased because the team won, the players did a great job and everyone enjoyed the game.
"Before the international break we played against United, Steaua and West Ham. We were the best in the world. We lost against Southampton and were the worst in the world but today we won and we're the best. You have to have balance. We knew it could be like this, we could win or lose, but we have to carry on.
"The priority is the top four, but we have to approach every competition trying to win. We had two games in less than 48 hours so had to manage the squad. We don't have too many players in some positions and we have to manage. I think we did it really well.
"The race for the top four will be until the end of the season. We're in the top four with a game in hand, we're in a very good position, the semi-finals of the FA Cup and the quarter-finals of the Europa League. I think it's a great season at the moment."
Chelsea will face another Manchester outfit at Wembley in the semi-finals, in the form of 2011 winners City, and Benitez admits that promises to be another testing tussle.
He added: "It cannot be more difficult this year. But if you want to win you have to play the best teams. United is one and City is another. It's another challenge and we will see."