Barcelona have lodged an official complaint to the Royal Spanish Football Federation (RFEF) over VAR's failure to award Ernesto Valverde's side a penalty during their 2-2 draw with Real Sociedad on Saturday.
La Blaugrana slipped up in the title race ahead of their colossal showdown with Real Madrid next week, as Alexander Isak's second half strike opened the door for Los Blancos to move into top spot should they overcome Valencia on Sunday.
It was the home side who went in front when Sergio Busquets felled
Antoine Griezmann and Luis Suarez then turned the game around for the visitors, but Barça were left aggrieved in the dying stages when Gerard Pique went down under a similar looking challenge to the one on Llorente in the first half, but referee Gil Manzano opted against awarding it.
VAR wasn't called into action, despite multiple protests, and Mundo Deportivo have now confirmed that the club's president, Josep Maria Bartomeu, has sent a letter to the RFEF explaining his outrage at the non-use of the technology.
"I'm not a referee, I don't know if it was a penalty," Valverde said, via Marca.
With Madrid up next for his side, the Spanish tactician was in no doubt that the clash will be a physical encounter, something Valverde has planned for by resting certain players in recent weeks. However, he refuted claims that squad rotation was the cause of Saturday's result, insisting his side weren't looking ahead to El Clasico and were focused on Real Sociedad.
"What do you think? We're dying here on the bench," he added. "