The first of the two Pyrenean days smiled on a Frenchman.
Among the day's breakaways, Nans Peters was the first at the top of Port de Balès before losing company on the descent to the last rider to keep pace, Russian Ilnur Zakarin.
The AG2R La Mondiale rider then held the shock in the ascent of the Col de Peyresourde to win at the age of 26, and for his first participation, his first stage in the Tour de France, the 2nd by a Frenchman this year after that of Julian Alaphilippe last Sunday.
Adam Yates retains the yellow jersey.
In the process, Romain Bardet takes back three seconds.
The big loser of the day among the favorites is called Thibaut Pinot, in great difficulty in the climb of Port de Balès.
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Classification Tour de France 2020