Stefan Mitrovic's own goal allowed Valencia to take a big step towards qualification from Champions League Group H as Gent were beaten 2-1 at the Mestalla.
The hosts lead through Sofiane Feghouli's early opener but Thomas Foket equalised with a superb effort for the Belgians before half-time.
However, a Jose Gaya shot struck Mitrovic and spared Los Che's blushes with 73 minutes on the clock, helping the Spanish side move closer to a place in the last 16 of the competition.
Valencia started well and Shkodran Mustafi should have put them in front but he headed over the crossbar from a corner.
They were soon ahead though when Feghouli bundled the ball over the line from Joao Cancelo's right-wing cross after 15 minutes.
The hosts were in the ascendancy and visiting goalkeeper Matz Sels produced a string of fine saves to keep Gent in the game -- most notably a double stop diving to his left to deny Filipe Andre Gomes before recovering to turn behind Dani Parejo's follow-up.
Gent had offered little as an attacking force but five minutes before the break Foket got on the end of a Renato Neto ball over the top and blasted his shot beyond home keeper Jaume Domenech and into the roof of the net.
Gent grew in confidence in the second half and Valencia were fortunate to sneak the win when Cancelo's cross hit the crossbar and fell to Gaya, whose shot went in off the unfortunate Mitrovic.
Jaume denied Thomas Matton late on to preserve a precious three points for Valencia.
The result sees Valencia remain three points adrift of group leaders Zenit St Petersburg, who beat Lyon 3-1 in Russia, while Gent are still without a win.