The Argentine superstar also scored Barcelona's 5,000th goal on February 1, 2009, at Racing Santander.
"The first time he hit the bar, the second time, goal number 6,000".
However, Messi's free kick paved the way for Barcelona to open their defence of the title with three points, with substitute Coutinho rifling home from inside the area inside the final 10 minutes.
"We expected Alaves would be hard because they tighten up at the back and it was like that in the first half, but in the second we found more space and the goals arrived", said Roberto. 64' - GOALBARCELONA - Messi sneaks a free kick under the jumping wall and tucks it into the corner to give the hosts a 1-0 lead.
Messi had clanged the crossbar in the first half from a set piece and Ousmane Dembélé forced the visiting goalkeeper, Pacheco, to make an impressive save while Luis Suárez looked ineffective.
The champions were far too ponderous in possession throughout, with midfielders reluctant to run from deep and Dembele too often surrendering the ball when trying to stretch Alaves' rigid 4-5-1 set-up.
Real Sociedad won 2-1 at Villarreal despite going a goal down. Unfortunately for him, his side lost 2-1 at home to Real Sociedad. No one did. It was like the one he scored against Girona last season. But Celta Vigo were back on level terms early in the second half when Aspas converted a cross from left-back Junior Alonso.
Real Madrid get their league campaign under way on Sunday, at home to Getafe (21:15 BST).
Atletico Madrid - last season's runner-up - visits Valencia on Monday.
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