If Real Madrid can play with full team and Benzema has no bad issue (injured), I also think that Real Madrid has a bigger chance to win. Benzema looks to play better than Lewandowski, and other Real Madrid attackers look more productive than Barcelona attackers (scored more goals). In this matter, we can assume that Real Madrid has a better attacking line. For midfielders, I also think that Real Madrid is better than Barcelona. It is only about the defenders, if Real Madrid defenders perform well, Real Madrid should defeat Barcelona. In the previous match, Real Madrid defenders played under performance.
Yes, even though they are superior, there is no guarantee for Barcelona to beat Real Madrid again. Real Madrid visited Camp Nou with high ambitions to steal victory and qualify for the final. Carlo Ancelotti is aware that only the Copa Del Rey is the only domestic title his team has the chance to win, because for the La Liga title it seems that hope is very slim. Xavi certainly has to be wary of the drums of war that Benzema and friends are beating, because Real Madrid has good capital after winning a landslide victory over Valladolid.
Real Madrid have to wins at least 2 goals margin if they want to advance to the final match and it's quite hard for them because we all know Barcelona were very strong at their home and if i am not mistaken they even only lose once in all competitions at that time from Bayern and besides that Barcelona defense were very strong and during this season it's rare to see Barcelona conceded more than 2 goal in a single match
I think both teams will be considers this is important match for them because for Xavi if Barcelona will be able to beat Real Madrid i think he could bringing Barcelona to gets double winner Laliga trophy and Copa Del Rey even so with Madrid that the trophy from this competition can be safe Ancelotti career because the team such as Real Madrid won't ended this season without the trophy
For this match Barcelona obviously the favourite but indeed there is no guarantee Madrid will lose again from them and Madrid in the positive trend especially after win with big scores from Valladolid and Benzema also looks onfire after scores hattrick on that match