The short 130km stage was another fast and furious one in France, with an uphill start setting the tone. Dylan van Baarle and Luke Rowe rode strongly at the head of the peloton for the majority of the day, sharing pace making duties with Bora Hangsrohe ahead of the final climb.
All eyes were on the hors categorie Valmorel and the second summit finish in as many days but attacks were late to fire on the 12km climb.
Yates opened proceedings with a dig 4km from the finish. Thomas was quick to get on his wheel, before Martin caught and countered.
At that point Geoghegan Hart hit the front and put the hammer down, impressing for the second day running. His effort halved the gap to Martin and as he pulled off under the flamme rouge, Thomas went.
Romain Barder (AG2R La Mondiale) was able to stay with the 32 year old for a few seconds before losing the wheel and Thomas continued his pursuit of Martin, rolling in just four seconds behind the Irishman to put himself in a dominant position with two days to go.
Speaking after digging deep to finish 21st on the day, Moscon said: “It was a very hard stage. The uphill start was very tiring. From the gun, I still felt yesterday’s stage in my legs - I hadn’t fully recovered and I didn’t have one of my best days on the bike.
“Of course I’m still happy with how things went because we still have the leader’s jersey with Geraint. We can really play for the overall victory. There are two hard stages left with a lot of climbing.”