Atletico Madrid effectively handed the LaLiga title to Barcelona as a 3-0 loss at Real Sociedad on Thursday left them at risk of slipping out of second.
A classy double from substitute Juanmi added to Willian Jose's first-half opener in a result that means Barca can confirm themselves as champions with a win at Deportivo La Coruna next weekend, seven days before Real Madrid head to Camp Nou for El Clasico.
Atleti's third away league defeat in their last four on the road boosts Madrid's hopes of leapfrogging their city rivals, though, with Diego Simeone's men ahead by just three points with five matches remaining.
Simeone had spoken pre-match of his desire to push Barca as far as possible in the title fight to help convince Antoine Griezmann he is in the right place.
But a lifeless display from player and team alike will have done little to strengthen Atleti's pitch as the France forward failed to fire against his ex-employers, held to a first blank in five league outings.
Instead, it was interim Sociedad boss Imanol Alguacil - now unbeaten in his four matches in charge - who enhanced his claims to retain his position on a full-time basis amid suggestions the club are eager to turn to Paris Saint-Germain coach Unai Emery.
Atleti needed 20 minutes to pose any sort of threat to the fit-again Geronimo Rulli, a deflected Diego Godin header comfortably held by the goalkeeper in his first appearance for two months.
Godin had earlier made a timely intervention to snuff out a promising Sociedad opening, but the visitors did not escape punishment for their sluggish start. Willian Jose was left free to drill the opener in off the base of the left post from Adnan Januzaj's clever cutback.
Griezmann immediately blazed over a half-volley at the other end and his lack of conviction was contrasted by Januzaj, who went close to doubling the margin with a fierce effort that flashed across the face of goal.
Simeone responded by introducing Fernando Torres in place of Angel Correa at the interval, but the presence of the departing striker inspired little impetus after the restart.
Jan Oblak got down low to smother another effort from the influential Januzaj, before Torres and Sime Vrsaljko missed the target with a pair of quickfire headers.
Willian Jose drove a good opportunity wide, but the miss never look like coming back to haunt Sociedad. The Brazilian striker instead turned provider in the 80th minute, his fine touch freeing Juanmi - who replaced Mikel Oyarzabal eight minutes earlier - for for a delightful dinked finish.
Juanmi rounded off a comprehensive victory with a well-taken header in the second minute of stoppage time, looping in his side's third from Alberto de la Bella's measured cross to put Barca on the brink of glory.
