Match ends, Valencia 2, Barcelona 0.
Quique Setien suffered his first defeat as Barcelona manager as Valencia claimed their first home win over the Spanish champions since 2007.
The hosts broke the deadlock when Jordi Alba deflected Maxi Gomez's powerful strike past Marc-Andre ter Stegen.
Gomez, who had a first-half penalty saved by Ter Stegen, completed the scoring in the second half.
There were unsavoury scenes before the game as rival fans clashed outside the Mestalla Stadium.
Setien had enjoyed a good start to his Barca reign, guiding the club to victories over Granada in La Liga and UD Ibiza in the Copa del Rey round of 32.
The visitors were quick to gain a stranglehold on possession but were almost non-existent as an attacking force in the first half, with Valencia enjoying the better of the early chances.
Los Che were gifted a golden opportunity to take the lead when Gerard Pique felled Gomez inside the penalty area, but the Uruguayan's spot-kick was superbly palmed to safety by Ter Stegen.
The former Borussia Monchengladbach goalkeeper had to be on his toes moments later to parry another Gomez effort on to the woodwork, before tipping Kevin Gameiro's follow-up past the post at full stretch.
Barcelona started the second half with greater purpose and Ansu Fati almost fashioned an opening after combining well with Lionel Messi, but the teenager could only poke his shot wide of Jaume Domenech's right-hand post.
Messi appeared eager to take matters into his own hands as the second half progressed, dragging a fierce low effort wide of the far post before heading off target from Antoine Griezmann's delivery.
Gomez ended the visitors' hopes of a late revival with 13 minutes remaining, curling into the far corner after Ferran Torres had broken clear down the right wing.
Former Arsenal defender Gabriel Paulista thought he had made it 3-0 late on, but the Brazilian's volley was disallowed for an infringement inside the Barcelona box.
Second-placed Real Madrid can move three points clear of Barcelona at the top of La Liga if they win their game in hand at Real Valladolid on Sunday.
- 17CoquelinBooked at 54mins
- 8SolerSubstituted forSobrinoat 90'minutes
- 9GameiroSubstituted forRodrigoat 59'minutes
- 22GómezSubstituted forCostaat 80'minutes
- 1ter Stegen
- 3PiquéBooked at 10mins
- 23UmtitiBooked at 43mins
- 5BusquetsBooked at 52mins
- 31FatiSubstituted forColladoat 85'minutes
- 21de JongSubstituted forRakiticat 85'minutes
- 8ArthurSubstituted forVidalat 56'minutes
- 2Nélson Semedo
- Jesús Gil Manzano
- Shots on Target
Second Half ends, Valencia 2, Barcelona 0.
Offside, Barcelona. Samuel Umtiti tries a through ball, but Antoine Griezmann is caught offside.
Attempt saved. Lionel Messi (Barcelona) left footed shot from the left side of the box is saved in the bottom left corner. Assisted by Arturo Vidal.
Attempt missed. Lionel Messi (Barcelona) left footed shot from outside the box is too high from a direct free kick.
Lionel Messi (Barcelona) wins a free kick in the attacking half.
Foul by Geoffrey Kondogbia (Valencia).
Foul by Samuel Umtiti (Barcelona).
Rubén Sobrino (Valencia) wins a free kick on the right wing.
Substitution, Valencia. Rubén Sobrino replaces Carlos Soler.
Foul by Arturo Vidal (Barcelona).
Geoffrey Kondogbia (Valencia) wins a free kick in the defensive half.
Attempt blocked. Ivan Rakitic (Barcelona) left footed shot from the centre of the box is blocked.
Attempt saved. Lionel Messi (Barcelona) left footed shot from outside the box is saved in the bottom right corner. Assisted by Ivan Rakitic.
Substitution, Barcelona. Álex Collado replaces Ansu Fati.
Substitution, Barcelona. Ivan Rakitic replaces Frenkie de Jong.
Corner, Valencia. Conceded by Samuel Umtiti.
Offside, Valencia. Jaume Costa tries a through ball, but Ferrán Torres is caught offside.
Substitution, Valencia. Jaume Costa replaces Maxi Gómez.
Foul by Sergio Busquets (Barcelona).