The France international was speaking after Los Che demolished AZ 4-0 at home (5-2 on aggregate) to reach the last four of the competition.
The evening was a particularly proud one for Rami as the centre-half grabbed a brace, the first of his career.
"The tie against Atletico Madrid will be a very difficult one," he told Canal Plus after the game. "We will play against a very good side and also against one of the best strikers in the world [Falcao] along with Benzema.
"It will be necessary to work and make a big effort and we will see what our destiny holds for us."
Valencia return to Liga action on Sunday when they make a visit to the Santiago Bernabeu to face Real Madrid.