Roglic is the reigning title holder in Vueltan and was on the verge of winning the Tour de France before losing the lead on the penultimate stage and finishing second.
The Slovenian has come out on top in France and lined up great races since then.
Today's mostly flat stage over 185 km with finish in Suances on the Bay of Biscay was not thought to give any changes in total but Roglic came as a shot from a cannon on the uphill run and got ten bonus seconds for the final clear victory.
- It is never easy to win but today I had my legs.
It does not change anything for the stable.
We must continue to take advantage of the momentum, says Roglic according to AP.
One and two have exactly the same time
The former leader Richard Carapaz was three seconds behind on today's stretch and before the continuation, the two leaders have exactly the same time.
At the Giro d'Italia, they separated the total time by studying the pace stages.
Vueltan only has one tempo stage that comes later and Roglic leads thanks to better placements on the stages that have been run.
A break-in of four cyclists had a gap of twelve minutes for a while but was caught.
The race, which is run in an almost closed Spain with a curfew between 23.00 and 06.00, finishes in Madrid on 8 November.