There were plenty of eyes on 19-year-old Real debutant Fran Gonzalez, but the goalkeeper wasn’t helped to settle in as he rushed to keep an unconvincing Lucas Vazquez backpass in play.
Opposition goalkeeper Giorgi Mamardashvili then faced a Vinicius Junior penalty after Kylian Mbappe had gone down under pressure from Cesar Tarrega, and he outfoxed the Brazilian to deny what turned out to be a tame spot-kick with his legs.
Just two minutes later, Mouctar Diakhaby domineeringly met Andre Almeida’s corner with a superb header that left Fran helpless and gave the visitors a shock lead.
After Almeida and Diakhaby had teamed up for the opener, their mix-up almost resulted in a calamitous own goal from the latter, but the centre-back’s blushes were spared due to Mbappe being offside.
Los Blancos’ disappointment was almost swiftly compounded further when Tarrega flicked his header from a corner marginally wide. The hosts still moved the ball patiently against a resolute Valencia backline, but Mbappe was constantly looking to find an equaliser, hitting one shot that was deflected agonisingly wide and seeing another attempt tipped over before also hitting the woodwork.
Jude Bellingham came close before the break, but Los Blancos were level within five minutes of the restart as Bellingham flicked Luka Modric’s corner to the back post, where Vinicius Junior turned it into the roof of the net.
The pressure built on Los Che, with Diakhaby blocking a shot from Rodrygo, who then headed wide shortly after.
The visitors still forced Fran into a save when Tarrega’s header hit Diakhaby, although they soon returned to defensive duties, with Mamardashvili stopping Federico Valverde before Jesus Vazquez reacted brilliantly to clear the ball ahead of Lucas Vazquez.
Endrick and Rafa Mir then had an attempt blocked at either end, but the latter then delivered a pinpoint cross for Duro to head home a dramatic winner.
Mamardashvili then rushed out to halt Antonio Rudiger and ensure Valencia took the points, establishing a five-game unbeaten run for the first time since October 2022 to go seven points above 18th-placed Leganes.
They also inflicted a damaging defeat on Real Madrid, who could be six points behind leaders Barcelona by the end of the day, having lost two of their last five LaLiga contests.
Flashscore Man of the Match: Giorgi Mamardashvili (Valencia)