Barcelona lost an eight-goal thriller as Villarreal struck twice deep into stoppage time to leave Xavi's side 10 points off the top of La Liga.
The hosts had fought back with three goals in 11 minutes to lead after trailing 2-0 until the hour mark.
But Villarreal equalised with six minutes remaining and Alexander Sorloth put the visitors back in front in the ninth minute of stoppage time.
Jose Luis Morales then added a fifth after 102 minutes to seal victory.
Defeat leaves defending champions Barcelona third in the La Liga title race, 10 points behind leaders Real Madrid and eight points off Girona in second.
It comes after they were knocked out of the Copa del Rey quarter-finals in a 4-2 defeat by Athletic Bilbao on Wednesday.
It is Barcelona's third loss in five matches, with their other defeat in that run coming against Real Madrid in the Spanish Super Cup, which they lost 4-1.
After Gerard Moreno's first-half opener and Ilias Akhomach's 54th-minute goal, Barcelona produced a stunning comeback through Ilkay Gundogan, Pedri and an Eric Bailly own-goal.
But, following Goncarlo Guedes' 84th-minute equaliser for Villarreal, the hosts were left exposed in their pursuit of a late winner and ultimately punished by Sorloth's and Luis Morales' late goals.
Real Madrid came from behind to beat Las Palmas 2-1 on Saturday and moved back above Girona, who play struggling Celta Vigo on Sunday (13:00 GMT).
Latest Stories
-
I want to focus more on my education – Chidimma Adetshina quits pageantry
3 hours -
Priest replaced after Sabrina Carpenter shoots music video in his church
3 hours -
Duct-taped banana artwork sells for $6.2m in NYC
3 hours -
Arrest warrants issued for Netanyahu, Gallant and Hamas commander over alleged war crimes
3 hours -
Actors Jonathan Majors and Meagan Good are engaged
3 hours -
Expired rice saga: A ‘best before date’ can be extended – Food and Agriculture Engineer
3 hours -
Why I rejected Range Rover gift from a man – Tiwa Savage
3 hours -
KNUST Engineering College honours Telecel Ghana CEO at Alumni Excellence Awards
4 hours -
Postecoglou backs Bentancur appeal after ‘mistake’
4 hours -
#Manifesto debate: NDC to enact and pass National Climate Law – Prof Klutse
4 hours -
‘Everything a manager could wish for’ – Guardiola signs new deal
4 hours -
TEWU suspends strike after NLC directive, urges swift resolution of grievances
5 hours -
Netflix debuts Grain Media’s explosive film
5 hours -
‘Expired’ rice scandal: FDA is complicit; top officials must be fired – Ablakwa
6 hours -
#TheManifestoDebate: We’ll provide potable water, expand water distribution network – NDC
6 hours