Match ends, Barcelona 2, Valencia CF 3.
Barcelona lost at home in the league for the first time since April 2012 as Valencia ended the league leaders' run of 25 successive wins at the Nou Camp.
Alexis Sanchez gave Barca the lead before Dani Parejo swept home and Pablo Piatti headed in for the visitors.
Lionel Messi made it 2-2 from the penalty spot after Ricardo Costa had handled, but Valencia grabbed a famous win when Paco Alcacer slotted in.
The La Liga champions were also reduced to 10 men when Jordi Alba was sent off.
The former Valencia player was dismissed for a body-check on Sofiane Feghouli 13 minutes from time.
Defeat was Barcelona's first at home in the league since a 2-1 loss to Real Madrid in April 2012.
"I would say to them [the Barcelona players that everything continues, that we may lose the leadership of the league, but that we will still continue to fight," said Barcelona manager Gerardo Martino.
"We will try to recover the lost ground on our title rivals. We conceded chances to Valencia and they took advantage of them. We need to keep going and keep in mind how much this hurt us today."
Barcelona remain top of the table on goal difference with 54 points, from Atletico Madrid, who play Real Sociedad on Sunday at 1800 GMT.
Real Madrid, who have won their last five league matches, are a point behind and are at Athletic Bilbao on Sunday (2000 GMT).
- 22Alves da Silva
- 18AlbaBooked at 78mins
- 16BusquetsBooked at 90mins
- 14MascheranoBooked at 79mins
- 6HernándezSubstituted forIniestaat 65'minutes
- 4FábregasSubstituted forTelloat 77'minutes
- 13Pinto Colorado
- 24Roberto Carnicer
- 1Alves CarreiraBooked at 90mins
- 15Fuego Martínez
- 20Moreira da CostaBooked at 53mins
- 16AlcácerSubstituted forVargasat 73'minutes
- 21ParejoBooked at 45minsSubstituted forHerrero Javaloyasat 90+3'minutes
- 2PiattiSubstituted forNicolás Cartabiaat 87'minutes
- 7Gonçalves Oliveira
- 24Herrero Javaloyas
- 28Nicolás Cartabia
- 30Portugués Manzanera
- Pedro Jesús Pérez Montero
- Shots on Target
Second Half ends, Barcelona 2, Valencia CF 3.
Sergio Busquets (Barcelona) is shown the yellow card.
Diego Alves (Valencia CF) is shown the yellow card.
Substitution, Valencia CF. Míchel replaces Daniel Parejo.
Attempt missed. Lionel Messi (Barcelona) right footed shot from the centre of the box is close, but misses to the left. Assisted by Andrés Iniesta.
Attempt blocked. Lionel Messi (Barcelona) left footed shot from outside the box is blocked. Assisted by Dani Alves.
Foul by Javier Mascherano (Barcelona).
Daniel Parejo (Valencia CF) wins a free kick on the right wing.
Foul by Dani Alves (Barcelona).
Javi Fuego (Valencia CF) wins a free kick in the defensive half.
Substitution, Valencia CF. Fede replaces Pablo Piatti.
Corner, Valencia CF. Conceded by Andrés Iniesta.
Corner, Valencia CF. Conceded by Javier Mascherano.
Foul by Alexis Sánchez (Barcelona).
Jeremy Mathieu (Valencia CF) wins a free kick in the defensive half.
Attempt missed. Dani Alves (Barcelona) right footed shot from outside the box is close, but misses to the left. Assisted by Lionel Messi.
Attempt missed. Sofiane Feghouli (Valencia CF) right footed shot from outside the box misses to the left. Assisted by Javi Fuego following a corner.
Corner, Valencia CF. Conceded by Gerard Piqué.
Javier Mascherano (Barcelona) is shown the yellow card for hand ball.