Atletico had delayed Barca’s title party earlier in the day as they scraped past strugglers Real Valladolid 1-0 after surviving late VAR penalty drama.
Joaquin Fernandez’s own goal put Atletico ahead midway through the second half, but they had to endure a nervy final few minutes in which Jan Oblak had to be at his best and they survived a late VAR check over what looked like a clear Santiago Arias handball in the area.
“It’s controversial, a ball that hits the hand and the referee’s decision is to see if it’s voluntary or not,” said Saul Niguez, whose cross led to their fortunate winner.
Diego Simeone’s side are nine points ahead of local rivals and reigning European champions Real Madrid, who travel to Rayo Vallecano on Sunday amid increasing speculation they will respond to a disappointing season by swooping for Eden Hazard and Neymar.
“It’s what we deserve, no more, no less. We’ve come so far,” added Saul.
“There were moments when we wanted to be first and others that I would say no, that’s what we deserve.”
Valladolid meanwhile stay 17th, just one point and a place away from the relegation zone after a match they will feel they were unlucky to lose.
Earlier on Saturday, Athletic Bilbao and Alaves did their chances of European football next season no favours with a 1-1 draw in the Basque Country.
Seventh-placed Bilbao are five points away from the Champions league places — with Alaves a further three points back — and could also see Valencia and Sevilla take the Europa league further away from them when they take on Eibar and Girona.