Messi's 2 goals help Barcelona advance

Coutinho, dressed in a black shirt dotted with white stars, was in the stands at the Camp Nou for the first time since his 160 million-euro (192 million) move from Liverpool. It didn't take long for the Brazilian star to appreciate the playing riches on show on the pitch. "The first half was extraordinary," said Barca coach Ernesto Valverde.

Level at 1-1 after the first leg, the three-time defending champions were 4-0 up by half-time.

Messi grabbed the opening two goals in the 13th and 15th minutes, both finished with a sublime first touch with his left foot, both created by Jordi Alba. Messi then returned the favour by setting up Alba to score past the hapless Sergio Alvarez in the Celta goal before Luis Suarez made it 4-0 on the night after 30 minutes when the Uruguayan burst through the defence.

The tie petered out in the second half but French international Ousmane Dembele showed why Barcelona paid 105 million euros for him last year when he dribbled past three defenders from the halfway line before being denied by a desperate tackle. Dembele did have time to set up the fifth goal of the night three minutes from the end when his corner was headed home from close range by an unmarked Ivan Rakitic.

"It's luxury to have Leo in the side, he's the best in history. We always look for each other to score goals and today we have done it twice," said Alba.

Earlier Thursday, Espanyol overturned a 2-1 loss in the first leg to defeat Levante 2-0 with Leo Baptistao and Gerard Moreno on target either side of half-time. Sevilla also progressed with a 2-1 win at home to

second-tier Cadiz for a 4-1 aggregate.