Barcelona Coach Ernesto Valverde took no chances after a 1-1 draw in the first leg, starting Messi in his first appearance in the tournament this season — he had rested for the first three cup games.
Messi quickly quashed any chance of Celta springing an upset. He swept Alba’s cross past goalkeeper Sergio Álvarez, who got a hand to the ball, and he followed up by firing home after another exchange of passes with Alba.
Messi then turned provider, lobbing a perfect pass behind Celta’s back line to meet a run by Alba, who chipped Alvarez to score.
“The connection between Messi and Alba is nothing new, it has been working for years,” Valverde said. “They look for each other and are happy to do so, because it is not just Alba assisting Messi. Messi also creates goals for Alba.”
Suárez scored in the 31st after pouncing on a poor pass by Pione Sisto, before Rakitic nodded one home at the end.
Barcelona extended its unbeaten run this season to 28 straight matches, dating to its losses to Real Madrid in both legs of the Spanish Super Cup in August.
Celta had drawn 2-2 at Barcelona in La Liga last month and had gone into Thursday’s match after holding Madrid to a 2-2 draw in the league last weekend.