Real Madrid are in danger of seeing their La Liga title bid collapse after falling 2-0 behind to Valencia in the first half at the Bernabeu.
Valencia looked confident for much of the early stages, but breathed a sigh of relief as the hosts came agonisingly close to taking the lead when Gareth Bale rattled the crossbar with a free kick.
Real tested the woodwork once again when Cristiano Ronaldo capitalised on some poor marking to head against the crossbar, and Valencia took full advantage of their fortune to break the deadlock a few moments later.
Jose Luis Gaya found enough space on the wing to deliver a dangerous cross and Paco Alcacer reacted quickest to poke the ball home from close range.
Their lead was doubled before the half-hour mark when Dani Parejo's inviting free kick found Javi Fuego, who used the space on offer to flick a header past the helpless Iker Casillas.
Despite continuing to look vulnerable to the counter, Real enjoyed long spells of possession and were only denied a goal by a diving save from Diego Alves when Bale targeted the top corner from long range.
A clever piece of play between Bale and Javier Hernandez almost allowed the hosts to reduce the deficit before the break, but the Mexican striker could only drag his effort against the post.
There was still time for more drama before the interval when Gaya pulled down Bale in the penalty area as both players looked to connect with a cross.
Ronaldo stepped up from 12 yards, but Alves guessed correctly to make the save as Valencia held on for a two-goal advantage at the halfway stage.
