Coutinho scored in the 5-0 rout.
"For me tonight is unforgettable," he said.
"It was always my dream to play here and win titles and this is my first trophy with Barcelona.
"The coach said that we needed to be focused from the first minute against a very good rival and we had a great first half.
"We want to win all the competitions and the Champions League wasn't possible this season. Today we are happy and we should enjoy the win."