Real Madrid claimed a 36th LaLiga title after Girona fought-back to beat Barcelona 4-2, a result that left Carlo Ancelotti's side with an unassailable lead in the standings.
Real Madrid, who have lost only once in the league this season, beat lowly Cadiz earlier on Saturday. They hold a 13-point advantage over second-placed Girona while Barcelona dropped to third with four matches remaining.
Real now can turn their attention to a LaLiga-Champions League double as they get ready to host Bayern Munich in the semi-final return leg on Wednesday after snatching a 2-2 draw in Germany last week.
It was an afternoon of celebration for Girona too as the win secured them a spot in Europe for the first time after they qualified for next season's Champions League.
A brace from substitute Portu helped surprise package Girona to humble their Catalan rivals for the second time this season. Girona had also beaten Barca away in December by the same score.
On Saturday Andreas Christiansen gave Barca the lead in the third minute before Girona hit back a minute later with LaLiga top-scorer Artem Dovbyk heading in the equaliser.
Robert Lewandowski put the visitors back in front from the penalty spot after Lamine Yamal was fouled inside the box just before the break and a wasteful Barca missed several chances to extend their lead early in the second half.
However, in the 65th minute, in his first action after coming off the bench, Portu netted the equaliser and Miguel Gutierrez scored from a rebound two minutes later to give Girona the lead. A stunning volley from Portu in the 74th minute secured the win.
"It's incredible to look at your shirt and experience this. There is nothing more beautiful than living this," an emotional Portu told DAZN with tears rolling down his face.
"I had a thorn in my side with this club. A few years ago, I experienced the other side, which was relegation and I felt very responsible because I played a lot. Today I made amends with the fans and I can smile again."
If Barcelona end up finishing outside the top two, it will be a further blow to the club which is facing mounting financial problems related to their massive wage bill, debt and Camp Nou stadium renovation project.
The champions and runners-up of the Copa del Rey and LaLiga contest the lucrative Spanish Super Cup in Saudi Arabia, with the winner bagging a potential 6.6 million euros.
With four matches remaining, Barca now rely on Girona slipping up if they are to have any chance of contesting the Super Cup.
"I am sad, disappointed. We have experienced both sides of the coin. Ineffectiveness have killed us once and again," Barca manager Xavi Hernandez, who last week announced he will stay in charge for another season, told a press conference.
"I'm the first to be angry with this situation, I understand the fans. Before being a coach, I was a fan. I understand our people's frustration."
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