The Bavarians and los Blancos are viewed by many as the form sides in Europe right now, but the former Arsenal captain does not see any reason for the Blaugrana to fear either
Los Blancos won by a 6-1 avalanche against Schalke, while reigning European champions Bayern defeated Arsenal 2-0 at the Emirates.
However, Fabregas claimed Madrid's game in Gelsenkirchen was effectively over the moment the capital club doubled their lead, while he still expects Pep Guardiola's men to have problems finishing off the Gunners at the Allianz Arena.
"The Champions League does not usually see this kind of results [Madrid's landslide win], but I was not impressed," the 26-year-old told Mundo Deportivo.
"Schalke surrendered with the scoreline at 2-0, right after they could have made it 1-1. Neither does Bayern winning the German league and cup 90 percent of the time mean anything to me.
"They have a momentary 2-0 lead against an English team. We shall see in the end."
The Catalan instead talked up the strength of his boyhood team, saying the Blaugrana will do everything they can to successfully defend their Liga title, as well as progress to the next stages of Europe's elite club competition.
"Barcelona is the world's most demanding club," he continued. "We must be more united than ever now. "We know that if our team plays at 100 percent then we can win almost every game.
"[Champions League opponents Manchester] City are still alive, as are Arsenal and Manchester United. The qualifiers are 180 minutes.
"We played a very good 90 minutes, but are aware another difficult game will follow. We found that out against Paris Saint-Germain [when they sneaked into the semi-finals last season on away goals]."
Gerardo Martino's team will be protecting a 2-0 lead when they take on City in the return leg at the Camp Nou on March 12.