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
-
Emirates and Parsys design pioneering new telemedicine station for inflight customers
28 minutes -
Pepsodent’s Month of Smiles: Bringing oral health to every Ghanaian
42 minutes -
Mahama reminds appointees to comply with Assets Declaration Law
53 minutes -
Every McDonald’s warned over staff sexual abuse
1 hour -
Abercombie & Fitch must pay for ex-CEO’s criminal sex trafficking defence
1 hour -
UN judge guilty of forcing woman to work as slave
1 hour -
‘There has to be some pain’ – Economist Joe Jackson defends new mining tax in 2025 Budget
2 hours -
Trump says anti-Tesla protesters will face ‘hell’
2 hours -
Putin sets out conditions for Ukraine ceasefire
2 hours -
Trump threatens 200% tariff on alcohol from EU
3 hours -
Judge orders Trump administration to give fired workers their jobs back
3 hours -
Measles cases pick up as RFK promotes unproven treatments
3 hours -
‘Not a fresh case, not a political attack’ – IMANI’s legal battle over Dampare’s removal
4 hours -
‘Wonnim Red’: Ghana’s opioid crisis
4 hours -
Mahama Cares will not replace free dialysis treatment – Minister assures
4 hours