The Catalan outfit enter the second leg as the slight underdogs following a 1-1 draw at the Camp Nou last week.
However, Fabregas believes that the Spanish champions "have enough quality" to book their spot in the final four of the competition.
"The key is to be together as a team. Individually we will give a lot because it is a big game and we hope to win a big tournament," Fabregas told Mundo Deportivo.
"We have done well in these games and we really want to win. That's our hope. It may be a harder game. When Atletico have to get a 0-0 they have good lines together in their team and don't have the pressure of their public.
"We have enough quality to beat them but we must compete at the same level. If we do, the quality is there to win."
Each of the four meetings between the two sides this season have ended in draws.