Atletico Madrid earned a scrappy 1-0 win at home to struggling Real Valladolid on Saturday which obliged Barcelona to win their game with Levante later on in order to clinch the La Liga title.
A win for Valladolid would have handed Barca the title before their kick-off at home to Levante but they were made to wait a few more hours to be crowned champions after second-placed Atletico provisionally closed the gap behind them to six points.
The game was decided by a glaring error from Valladolid defender Joaquin Fernandez, who appeared at the near post to try to clear a cross from Atletico's Saul Niguez but instead headed the ball straight into his own net.
"It was a tough game, difficult after playing [Wednesday] against Valencia," Atletico boss Diego Simeone said. "We were not as precise as the other day.
"They looked to counterattack with danger. Barca are tremendous and now to wait and see what happens tonight. Levante have a lot to play for so it will be a nice game. I'll watch it at home."
Valladolid went into the game one point and one place above the relegation zone and kept pursuing an equaliser late into the game.
They had a penalty appeal for a possible handball by Atleti's Santiago Arias turned down after a lengthy VAR review while Miguel de la Fuente and Oscar Plano were both thwarted late in the game by Atleti keeper Jan Oblak.
"It's always difficult from the other side," Simeone said. "When a team is playing for their lives it is logical to explain.
"It is up to the referee to explain why he did not whistle a penalty, but their complaints are completely understandable. We had handball incidents go against us at the Bernabeu and Villarreal this season."
It was Atletico's 15th win in 18 home games and took them on to 74 points after 35 games, while leaders Barcelona have 80 and will lift a 26th La Liga crown, their eighth in 11 seasons, with victory against Levante.