Real Betis will head into Thursday's Europa League group-stage opener away to Rangers on the back of a 5-0 hammering as hosts Barcelona moved to the top of La Liga.
The Betis head coach Manuel Pellegrini, who made four changes from the side that defeated Rayo Vallecano, remarked: "Of course it's a defeat that hurts a lot, physically and in terms of morale.
"With our tactics, when you go down by a couple of goals, you have to take risks."
Portugal forward Joao Felix fired the hosts ahead, with further goals from Robert Lewandowski, Ferran Torres and Raphinha sinking the visitors before fellow new arrival Joao Cancelo polished off the rout with a fine individual effort.
Betis, lining up with a back four composed only of former Barcelona players, played with attacking intent, unlike many other teams who will visit the temporary Olympic Stadium home of the Spanish champions.
Luiz Henrique sent a rasping effort across the face of goal and Ayoze Perez blasted into the side netting as Pellegrini's side started well before Barcelona edged ahead after 25 minutes.
Defeat leaves Betis in ninth place, five points behind Barcelona.