The city rivals meet with Liga champions Barca in imperious form as Gerardo Martino's target an astonishing 21st successive home league win, a run that continued with a 2-1 Clasico success last weekend.
Couple Barca's dominance in front of their own fans with the fact that Espanyol have left Camp Nou victorious just once in the last three decades, a 2-1 win in February 2009, and the odds of an upset appear slim at best.
A 2-2 draw between the two sides at Camp Nou in the penultimate game of the 2006-07 season, sealed by Raul Tamudo's 90th-minute effort, ultimately handed Real Madrid the title by virtue of a superior head-to-head record.
Indeed, the statistics surrounding Barcelona continue to make impressive reading.
Defender Adriano is a doubt for Barca after he suffered a hamstring injury during Tuesday's 3-0 win at Celta Vigo.
A run of one win in six league games has unravelled what was a promising start to the season for Javier Aguirre's side up until mid-September.
Casilla said: "We all know how important the derby with Barcelona is. We will go to Camp Nou and try to go all out.
"We'll have to play with intensity and try to stay focused for the entire 90 minutes.
"It's not going to be easy but it won’t be impossible. I have total respect for the Barca players, but I am not afraid of them.
"If you're scared of playing against Barcelona then you might as well stay at home."
