Barcelona were stunned as they conceded goals to Villarreal's Alexander Sorloth and Jose Luis Morales deep into stoppage time and lost 5-3 at home in a roller-coaster LaLiga clash on Saturday that was marked by more VAR controversy.
Barca remain in third place on 44 points, 10 behind leaders Real Madrid and eight adrift of second-placed Girona.
One week after the match between Real Madrid and Almeria included several controversial refereeing decisions that made the headlines, another two debatable VAR rulings in key moments of the match in Barcelona sparked furore.
Villarreal had an early effort by Gerard Moreno ruled out by referee Jose Munuera, who considered that a player in an offside position had interfered in the outcome, a decision that left Villarreal's players and manager Marcelino fuming.
But while Barca were in control with 70 per cent possession, it was Villarreal who opened up a two-goal lead with goals from Moreno in the 41st minute and Ilias Akhomach in the 54th.
First, they caught the hosts napping from a throw-in as Sorloth reacted quickly to deliver a fine low cross to Moreno who unleashed a first-time strike into the top corner before Ilias Akhomach made the most of defender Joao Cancelo's mistake.
But Barcelona fought back in an 11-minute spell through strikes by Ilkay Gundogan on the hour and Pedri eight minutes later before an own goal from Eric Bailly, who was trying to clear Frenkie de Jong's free kickin the 71st minute.
However, Villarreal responded as Sorloth started another quick counterattack with a great long pass to Goncalo Guedes, who collected the ball in his stride before firing home to equalise for Villarreal in the 84th.
Barca went on the attack and were awarded a penalty for a Santi Comesana handball in the 90th minute. However, after a VAR check the referee changed his decision despite the video replay clearly showing the ball had hit his elbow.
CONTROVERSY
With Barca pushing for a winner their defence was exposed and Sorloth and Morales struck to secure the points.
"In the end I am going to be sanctioned, I don't care, you analyse it yourselves, I don't want to generate more controversy," Xavi told DAZN.
"No excuses but that (Comesana penalty incident) decides the match. The fourth official told me it was a clear penalty. Munuera went to the monitor and said no. I don't want to talk any more, there are the images.
"The normal thing was that we would have won 4-2 but when you leave the rival alive that is what happens ... We have it in our hands and it's slipping away from us."
The win puts Villarreal into 14th place on 23 points.