If Real Madrid loses or draws today, Barcelona will clinch their 28th La Liga title before even playing.
In its history, Barcelona has clinched the league title twice without playing:
The first was in the 1990/91 season, when Barcelona won its first league title under Johan Cruyff as coach. The defeat came after Atlético Madrid lost 2-1 to Real Sociedad at Anoeta Stadium, handing the title to Barça before their match against Cádiz (which they won 4-0) and with four rounds remaining.
The second and final was in the 2008/09 season, Pep Guardiola’s first season as Barcelona coach. The team won the title after Real Madrid lost 3-2 to Villarreal in round 36, before Barça played their match against Real Mallorca. This defeat sealed the title for Barcelona without even playing.