The second Leg will hold in Camp Nou as rightly stated. It might be difficult for Madrid to surpass Barcelona in their home stadium. Al though the real victor for the Copa del Rey semi-final between this two rivals is not conclusive yet because Madrid can still turn things around but the fact the second leg will hold in Camp Nou makes Barcelona more advantageous than Madrid.
If Real Madrid can beat many big clubs in Champions League even when they were conceded first in the past season and in this season, it's not big matter for them to beat Barcelona at Camp Nou. If they play with their best, they can beat Barcelona there.
Barcelona are weaker than many big clubs in Champions League that is shown in their failed group stage and they were relegated to Europa League at which they failed in two play-off matches with Manchester United.
Anyway, the first El Classico in Coppa del Rey is very funny. From some personal clashes on field especially the moment between Vini and De Jong. Then a moment how Barcelona got the only and winning goal in the match.
Real Madrid are not in good form this season, I never expected them to lose to Barcelona in again, knowing full well that Spanish Laliga is out of thrr reach already and Champions League is not guarantee, the Copa de ray would have be there hope of getting something this season.
Eventually ageing began to show its bigger impacts on Real Madrid old players. They can not play well against time and ageing forever and this season can be a start of an ending for their old players. Their young players still rely on old players and Real Madrid will need one or two more seasons to see young players become more matured and can fully carry tough tasks. However, it is two sides of a coin, young players can not mature well if those old players are still there and get main positions in Real Madrid squad.