Barcelona suffered a dismal 2-1 home defeat to Osasuna on Friday 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.
Lionel Messi scored a stunning free-kick to cancel out Jose Arnaiz's opener but Osasuna, who had Enric Gallego sent off late on, secured all three points in stoppage time thanks to Roberto Torres' strike.
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.
What does it mean? Scale of Barca's task clear after woeful defeat
Madrid's win over Villarreal rendered Barca's result irrelevant but to lose so dismally on the day their bitter rivals win back the title will stick in the throats of their fans. Setien's side were exceptionally poor and can scarcely have any complaints with the defeat.
This side desperately needs some surgery during the close season if they are to reign again next season.
Messi magic in vain
Visibly frustrated by his side's inadequacies, the Barca icon looked unhappy throughout. Despite this, he scored yet another wonderful free-kick and was his side's best player by some distance.
Rakitic endures a game to forget
Croatia international Ivan Rakitic looked well off the pace in the middle of the pitch, regularly getting caught out by his busier and brighter Osasuna counterparts.
Barca wrap up their domestic season with a trip to Deportivo Alaves on Sunday, while Osasuna finish with a home clash against Mallorca on the same day.