Barcelona’s slim hopes for the Spanish league title all but ended after losing to Cadiz 1-0 at home in a match marked by protesting fans.
The fans were upset at Barcelona allowing Eintracht Frankfurt supporters to take over the Camp Nou Stadium in a Europa League match last week.
The first ever home loss to relegation-threatened Cadiz left Barcelona 15 points behind league leader Real Madrid with six rounds left.
The Catalan club, sitting in second place, has a game in hand but time is running out on their quest to win the league for the first time in three seasons.
Upset with the high number of Frankfurt fans at the Camp Nou on Thursday, one of Barcelona’s main fan groups left empty a section of the stadium behind one of the goals.
Only about 5000 tickets were sold to the visiting fans for Thursday’s match but nearly 30,000 made it to the Camp Nou to see their team defeat the Catalan club and advance to the Europa semi-finals.
Barcelona officials had already said the club would investigate how so many Frankfurt fans were able to buy tickets in sections reserved for Barcelona supporters.
Cadiz, who moved two points clear of the relegation zone, got the winner through Lucas Perez in the 48th minute.
They had won only one of their last four league matches, but haven’t lost to Barcelona in the competition in four straight games.
Before the losses to Eintracht and Cadiz, Barcelona were unbeaten in 15 straight matches in all competitions.
Making his 674th appearance for Barcelona, Sergio Busquets tied Andres Iniesta for the third most with the club, behind the 767 of Xavi Hernandez and the 778 of Lionel Messi.
Barcelona were without playmaker Pedri Gonzalez and defender Gerard Pique because of injuries, while defender Ronald Araujo was suspended.
Barcelona next visit sixth-placed Real Sociedad.