Cristiano Ronaldo's stoppage-time goal salvaged a 2-2 draw for Real Madrid as they followed Barcelona and Atletico Madrid in dropping points on a dramatic weekend in the title race.
Valencia twice led at the Bernabeu before Ronaldo stabbed the ball home with a deft backheel two minutes into five added on.
Barcelona's draw and Atletico Madrid's defeat left the door wide open for Madrid but they struggled to push through it as the top three all dropped points on the same weekend for the first time this season.
Jeremy Mathieu put Valencia ahead moments before half-time, and only six minutes after Sergio Ramos levelled before the hour mark, Dani Parejo put Valencia back in front.
After Ronaldo levelled, both he and substitute Alvaro Morata had golden chances for a winner but missed the target.
Defeat for Madrid would have left the Primera Division title in Barcelona's hands, but the draw leaves it too close to call.
Carlo Ancelotti's attacking line-up made clear Madrid's intent and they attacked from the off, with Diego Alves making a good save to deny Ronaldo just three minutes in before Karim Benzema was unlucky to miss the target when he stretched to reach a drilled cross from Gareth Bale moments later.
But Madrid's all-out attack was leaving space behind, and Valencia offered a warning in the 16th minute when a deep cross from the right found Parejo unmarked at the far post and his header had to be turned on to the crossbar and away by Diego Lopez.
If he had made any better contact the goalkeeper would have been powerless to deny him.
But for all Madrid's bustle they were struggling to create chances against a disciplined Valencia side, with Ronaldo cutting an increasingly frustrated figure as he appealed for penalties and free-kicks in vain.
He saw a powerful shot turned away by another fine Alves save in the 26th minute, and the goalkeeper turned over his header from the resulting corner.
He flashed a shot narrowly over just before the break and then tested Alves once more with a low shot, but instead it was Valencia who scored with a 43rd minute sucker-punch, Mathieu heading in from a corner moments after Lopez had done well to palm Sofiane Feghouli's shot away.
The atmosphere threatened to boil over early in the second half, with Angel Di Maria making wildly optimistic shouts for a penalty and earning a booking when he was denied.
But Madrid were doing a better job of creating chances by now, with Isco curling just wide before Alves made a brilliant save to keep out Ronaldo's low volley.
Rafael Varane's effort from a corner bounced agonisingly wide but the equaliser eventually came just before the hour when Ramos turned in Ronaldo's header from close range.
Parity would last only six minutes before former Madrid man Parejo silenced the Bernabeu with a drilled shot past Lopez after a cross deflected into his path.
Madrid were ever more desperate but Alves stood firm, denying Ronaldo more than once in the final 15 minutes.
But just when it seemed that he and Valencia had done enough, Madrid's talisman turned his body to meet Di Maria's cross and breathe fresh drama into the title race.
Earlier today Atletico Madrid's bid to be crowned Primera Division champions for the first time since 1996 suffered a major blow.
An early own goal from Filipe Luis saw Atletico fall behind at the Ciutat de Valencia and then David Barral added a decisive second for Levante midway through the second half.
Diego Simeone's men pushed hard to try and get something back in the closing stages but they could find no way through.