Kevin Gameiro's second-half penalty earned a laboured 1-0 win for Atletico Madrid at Deportivo Alaves, putting the onus on Barcelona to achieve a positive result in their clash with Deportivo La Coruna and wrap up La Liga's title race.
Runaway leaders Barca only need a point in their fixture later on Sunday to be crowned champions regardless of the outcome at the Mendizorroza.
But Diego Simeone's men at least maintained their slim hopes, with Gameiro netting from the spot after Fernando Torres had already fluffed his lines from 12 yards out, Mubarak Wakaso having conceded both penalties.
The disjointed performance from Atleti was perhaps to be expected, Simeone leaving out the likes of Antoine Griezmann, Jan Oblak and Saul Niguez as he prioritised Thursday's Europa League semi-final second leg with Arsenal, a tie which is locked at 1-1.
Real Madrid can also mathematically still catch Barca, but it would require a remarkable sequence of events to deny Ernesto Valverde's side the title.
It could have been a different outcome on the day had Lucas Hernandez been judged to have fouled Munir El Haddadi in the area, but Diego Costa also failed to score a good first-half chance for Atleti before Torres' missed penalty after the break, the away team finishing with 10 men after Angel Correa received a second yellow card in injury time.
Atleti's performance in the early stages had all the hallmarks of a side who knew their priorities now lay elsewhere and they had a huge let off in the 16th minute.
Lucas made a lung-busting recovery to atone for his failure to control a loose ball with Munir closing in on goal and seemingly bundled the on-loan Barca forward over in the area, but referee David Fernandez Borbalan ruled there was no foul.
The visitors struggled to get out of first gear, although a quickly taken free-kick led to Thomas Partey firing narrowly wide from 25 yards.
It took until the 42nd minute for debutant Alaves goalkeeper Antonio Sivera to be tested, Costa controlling Stefan Savic's punt over the top, turning inside Victor Laguardia and drawing the save with a low drive to the bottom-left corner.
The second half was a similarly forgettable affair, Vitolo briefly lighting up the match by cutting in from the left and unleashing a vicious effort that Sivera saved brilliantly – the goalkeeper seemingly hitting his shoulder on the post making the stop and having to be replaced by Fernando Pacheco.
Axel Werner made a fine fingertip save from John Guidetti's well-struck long-range effort, but it was Atleti that wasted the chance to open the scoring from the spot.
Wakaso's clumsy barge on Vitolo led to an inevitable penalty that Torres saw saved low to the keeper's right by Pacheco.
Incredibly, Wakaso conceded another spot-kick with 13 minutes remaining, this time handling Torres' half-volley, and Gameiro succeeded where his team-mate failed – striking straight down the middle to seal the points – despite Correa seeing red for a second yellow in injury time.
The title remains an unrealistic target, though, and Atleti's attention will be fully on the visit of the Gunners to the Wanda Metropolitano.
