Sergio Busquets scrambled an injury-time winner as Barcelona scraped past Valencia 1-0 to keep the pressure on Primera Division leaders Real Madrid.
Valencia had been well worth a point at the Mestalla, more than matching an off-colour Barca until the closing seconds of the game.
Lionel Messi was far from his best all night but finally produced a moment of quality as he found a wonderful ball for Neymar, whose header was saved only to be rammed home by Busquets.
It was his first goal of the season but a highly important one that keeps the Catalan side within two points of their rivals.
The match ended on a sour note, though, with Messi hit on the head by a bottle thrown from the stands as Barca players celebrated the winner.
Atletico Madrid clinched an eighth win in nine matches as they beat Deportivo La Coruna 2-0 thanks to goals from Saul and Arda Turan. But this was a day when violent scenes on the Madrid riverside before the game cast a dark shadow over football.
Running battles between rival supporters began at breakfast time and the Spanish league authorities made moves to postpone the match that began at midday local time.
One man died following the clashes, with the players and staff in the ground unaware of what had happened until after the final whistle.
Elsewhere, Sevilla scored four times in the final 25 minutes to record a morale-boosting 5-1 win over Andalusian rivals Granada at the Ramon Sanchez Pizjuan.
Sevilla, who had taken just one point from their previous three league games, went ahead through Carlos Bacca's 24th-minute strike but Granada were level by the break thanks to Youssef El Arabi's penalty.
That is the way the game stayed until the 66th minute, when Sevilla got their noses back in front through Ever Banega and then further goals from Bacca, Stephane Mbia and Kevin Gameiro completed a one-sided scoreline.
Villarreal move up to sixth place after producing a commanding performance to win 2-0 at bottom-side Cordoba.
Luciano Vietto hit his eighth goal of the season in all competitions to put the visitors in charge after 24 minutes and substitute Ikechukwu Uche put the game out of Cordoba's reach with 20 minutes to go with a simple finish from a corner.
Marcelino's side are starting to look like the side that finished in the top six last season again, while things are looking bleaker and bleaker for Miroslav Djukic's men, who are still without a win since returning to the top flight.