Royal Sociedad spoiled Barcelona's celebrations of their La Liga title in front of their fans, defeating the hosts 2-1 at Camp Nou on Saturday. Coach Xavi Hernandez's team had secured the title, their 27th, four rounds before the end after beating local rivals Espanyol 4-2 last week.
Sociedad opened the scoring early, with Mikel Merino finding the net in the fifth minute, and Alexander Sørloth extended the visitors' lead in the 72nd minute.
Robert Lewandowski scored a consolation goal for Barcelona in the dying moments, reinforcing his position at the top of the tournament's scoring charts with 22 goals.
Sociedad strengthened their position in fourth place with 65 points from 35 matches.