Title winners in Spain for each of the past two years, Barcelona surrendered their crown to Real Madrid this season and there might be fallout from that setback still to come.
At Alaves, however, it was a case of Barcelona showing they remain the most watchable team in Spain when they find their rhythm, a double from Messi and further goals from Ansu Fati, Luis Suarez and Nelson Semedo doing the damage.
Barcelona threw away their lead in the title race after a handful of post-lockdown draws allowed Madrid to steal a march and losing to 10-man Osasuna on Thursday reflected their misery, leading to questions being asked about coach Quique Setien's future. On Sunday, it was a thoroughly different story.
The visitors had already hit the Alaves goal frame three times, through Riqui Puig, Arturo Vidal and Messi, before they took a 24th-minute lead through Fati.
2 - Against Alavés, Riqui Puig (20y 341y) became the youngest @FCBarcelona player to provide two assists in a single @LaLigaEN game since Thiago Alcántara against Villarreal in August 2011 (20y 140d). Hope. pic.twitter.com/m3g9SZFeNl— OptaJose (@OptaJose) July 19, 2020
Messi was the creator, with his cross from the right having the sting slightly taken out of it by a minor deflection before dropping perfectly for Fati to crack into the bottom-right corner.
The second goal in the 34th minute came when Barcelona burst at pace and located their talisman in the centre of the penalty area.
Puig dutifully laid the ball into Messi's path from the left, and after shimmying delightfully to deceive goalkeeper Roberto Jimenez, the Argentinian stroked the ball home from close range.
Vidal had a header well saved by Roberto from Messi's terrific cross, before Suarez made it 3-0 in the 44th minute, nodding home after great link-up play from Messi and Jordi Alba.
Semedo replaced the injured Clement Lenglet early in the second half and left his defensive station to surge into the Alaves box and smash home a fourth goal in the 57th minute.
Messi - who else? - guided home a cross from Alba in the 75th minute, and suddenly Barcelona were all smiles.