I've not been nervous since the Pep vs Mou clasicos. We've mostly owned them under Lucho and EV (except for those first two Supercopa clasicos when he took over after the whole Neymar drama) but tbh I'm usually more comfortable when we play them at our training ground in Madrid than at Camp Nou.
Also, 8 players could make their El Clasico debut. Neto will start for sure.
With Alba returning Dest probably won't start but could come off the bench, the same for Pjanić. Pedri and Trincao were usually Koeman's first subs so far so I expect them to play as well. Puig, Araujo and Firpo will probably need to wait for the next time.