Barcelona suffered a dismal 2-1 home defeat to Osasuna on Thursday as they relinquished their LaLiga title to Real Madrid with a whimper.
Madrid secured their first championship since the 2016-17 season courtesy of a 2-1 win over Villarreal, opening an insurmountable seven-point gap over Barca with just a game to play.
With an injured Antoine Griezmann not in the squad and Luis Suarez starting on the substitutes’ bench, Quique Setien’s side looked bereft of ideas against their spirited visitors.
Barca started sluggishly and were duly punished after 16 minutes when Arnaiz superbly half-volleyed Pervis Estupinan’s cross past Marc-Andre ter Stegen at his near post.
Jon Moncayola whipped wide from just outside the penalty area soon after as the visitors threatened to extend their lead.
Barca belatedly woke from their slumber as the half wore, Messi going closest to scoring a leveller before the interval with a free-kick that crashed against the crossbar.
The hosts started the second half with a vigour that had been missing from their first-half display, with Messi firing straight at Sergio Herrera after a smart one-two with Ansu Fati.
There was little the Osasuna goalkeeper could do shortly after the hour mark, Argentina international Messi bending home a glorious free-kick from 25 yards to draw the hosts level.
Gallego received his marching orders 13 minutes from time after a VAR review deemed he had elbowed Clement Lenglet in an aerial challenge.
The visitors had the last laugh against their forlorn opponents, though, as Torres scored on the breakaway in stoppage time to seal a memorable away win that also summed up Barca’s poor campaign.