The matches against Bilbao and Mallorca are something that Real Madrid must win before El Clasico, so if both can be won then it doesn't matter if Real Madrid loses in El Clasico. However, it would certainly be dangerous for Real Madrid if they lost one of the matches against Bilbao and Mallorca, they would be in danger of losing points in El Clasico too.
Real Madrid should be able to overcome Bilbao quite well. Moreover, one of their main players, Bellingham, has also returned from his red card. So that he can compete optimally to strengthen his club. At least, he has a certain target after getting a ban not to play because of yesterday's red card which was quite unfair for him. This is a match that is also quite important for Real Madrid, so he and the entire squad must try very optimally so that their position will continue to be in the first place until the end. Moreover, Real Madrid will be the the host of the match at the Bernabeu.
Source: Bellingham