Barcelona dropped their first points in LaLiga this season as Rayo Vallecano fought back to secure a 1-1 draw at home to the champions in a testy encounter on Sunday where a faulty VAR system caused controversy.
Rayo substitute Fran Perez thrashed home a 67th-minute equalizer as he stole in unmarked at the back post from a corner after Lamine Yamal's 40th-minute penalty had put Barca ahead.
A malfunctioning VAR ensured the game was clouded in controversy after Pep Chavarria's challenge on Yamal, which led to the spot kick being awarded, could not be reviewed because the system was not working at the time.
Chavarria did make contact with Yamal's thigh but the penalty award might have been overturned on review.
Both teams had been informed of the faulty system at kick-off, but Rayo's vigorous protests over referee Mateo Busquets' decision ensured the rest of the clash at Estadio de Vallecas was played in a tempestuous atmosphere.
Indignant home supporters voiced their fury at every subsequent decision that went against their side.
"It is what it is. There are no excuses," Barca manager Hansi Flick told reporters. "VAR should work. I don't know what happened. There was no VAR for either of them. It's not my job."
Barca goalkeeper Joan Garcia made several outstanding stops to deny Rayo a win at the end of a week in which the club from the Madrid suburbs secured a place in the Conference League group phase on their return to Europe after 24 years.
Garcia made a point-blank save to deny Andrei Ratiu in the 12th minute and in the second half spectacularly denied efforts from Isi Palazon and a breakaway on goal by Jorge de Frutos.
Substitute Sergio Camello could have won the game for Rayo in the last minute but, with the goal at his mercy, he miscued his shot, allowing a grateful Garcia to gather easily.
For Barca, Daniel Olmo was guilty of missing a sitter soon after teenager Yamal's penalty had put the visitors ahead. He hit the ball over the top of the crossbar from close in, setting off an angry reaction from Flick.
"We lacked intensity and made too many mistakes. We can play better. We could have scored more goals," Flick said.
"But Rayo played very well. I'm not happy with my team today. We lost possession too often and we have to do better."
Barca had won their opening two games of the season, but the dropped points mean Real Madrid and Athletic Bilbao are the only two clubs with a 100% record after three matches. Rayo have four points from their opening matches of the campaign.
