The eighth stage of this year's cycling classic included three solid climbs on the 141-kilometer stretch between Cazères and Loudenvielle in the Pyrenees.
The Frenchman Nans Peters was involved in an early breakaway and kept all the way into goal while the others fell away.
The victory margin was 47 seconds ahead of the lightweight Tom Skujins.
After several breakout attempts behind Peters, the situation among the riders in the lead in the summary was finally stabilized and Adam Yates was able to keep the yellow leader's jersey.
The margin down to Slovenian Primoz Roglic is three seconds, with Guillaume Martin, France, another six seconds behind, as a new third.
The organizers have asked the audience to keep their distance during this year's Tour de France.
Despite the strict corona restrictions in France, however, the mountain roads were traditionally lined with spectators, almost as many as in a normal year, and not all with mouth guards.
It was a tough day for one of the biggest French favorites.
The home jumper Thibault Pinot, who rolled on the first stage, grinned badly during the stage and ended up far behind the lead in the finish.
Thus, his dream of becoming the first French overall winner of the Tour de France since 1985 is most likely crushed.
CLIP: Nasty bike crash (15/8)
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New nasty bike crash Photo: TT