كتب : وكالات
Barcelona are on top of the table with a two-point lead over Real, who are aiming to prevent their arch-rivals from winning a second consecutive title.
"Winning on Saturday is crucial," Chilean manager Pellegrini told the pre-match news conference.
"There are 14 matches left and 42 points in play. We cannot give up as long as there is a mathematical chance."
Pellegrini hopes Real can avenge their 2-1 defeat by Sevilla in the away fixture in October last year.
"Sevilla are as tough an opponent as all the other teams who have visited the Bernabeu. They beat us in the first match by playing very well. We hope to return the favor," he added.
"Every match is different, and both these teams are different than when they first met. Real Madrid have made a lot of progress and Sevilla are in very good form. I hope we can beat them this time round."