Real Madrid's harrowing campaign continued as they fell to a ninth defeat in La Liga and their first since coach Zinedine Zidane returned as they were deservedly beaten 2-1 away by a resurgent Valencia on Wednesday.
Madrid had played well until conceding, but lost momentum after the goal and Valencia continued to threaten into the second half, finally doubling their lead with a header by defender Ezequiel Garay from a corner in the 83rd.
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Karim Benzema headed in a consolation goal for Madrid in stoppage time, shortly after Zidane's side had a penalty decision overturned after a Video Assistant Referee (VAR) review ruled Sergio Ramos was offside.
Madrid are stuck in third on 57 points, 13 behind La Liga leaders Barcelona and five behind city rivals Atletico Madrid.
Valencia, who have reached the Copa del Rey final and the quarter-finals of the Europa League, have Champions League qualification in their sights after climbing up to fifth in the table on 46 points, one behind fourth-placed Getafe.
The win extended their unbeaten run to 17 games in all competitions, their longest stretch without defeat in their 100-year history.
It was Zidane's first away game since returning to the club after Santiago Solari was sacked last month, having won his first two games back against Celta Vigo and Huesca.
As he had promised ahead of the match, the Frenchman made sweeping changes from the team that had beaten Huesca, bringing back seven players including Toni Kroos, Luka Modric and Navas as Isco and Gareth Bale dropped to the bench.
Madrid dominated the early stages but could not turn their possession to chances and once Valencia took the lead through Guedes they rarely looked like letting it slip.
But Argentine Garay made up for his team mate's wastefulness by effectively sealing the points with a towering header from captain Dani Parejo's corner.