Küng (Groupama-FDJ) lapped the 14.3 km time trial course in 16 minutes and 12 seconds, more than 11 seconds faster than Movistar rider Nelson Olveira in second and 40 seconds faster than Thibault Guernalec in third.
Aussie Miles Scotson finished in fourth place with a time of 16 minutes and 52 seconds.
It was a big day for the french Groupama FDJ team which had three riders inside the top five finishers for the stage.
In addition to the first place, the French formation Groupama FDJ managed to place three of its cyclists in the top five of the day.
The win moves Kung 36 seconds ahead of Movistar's Spanish rider Enric Mas who has dropped to third in the general classification behind Oliveira.
Scotson remains the best Australian hope for GC honours 2 minutes and 26 seconds behind the lead in ninth place.
Küng will have work to do on Sunday if he is to take overall honours on a rather flat 91.2 kilometres, between Paterna and Valencia in the final stage.
