The stage exploded on the category two climb of the Cote de Mauvagnat, which peaked with 15km to go, as an elite group of seven riders came to the finish together.
And it was the 24-year-old Garmin-Sharp rider who took the sprint in Brioude ahead of Davide Malacarne (Europcar) and Gorka Izaguirre (Euskaltel).
The Team Sky duo of David Lopez Garcia and Richie Porte followed ahead of Romain Bardet (AG2R) and Andriy Grivko (Astana).
Overnight leader Elia Viviani was distanced on the ascent and lost nearly three minutes so Talanksy now leads by three seconds on GC from Grivko and Malacarne with Sylvain Chavanel a further second back in fourth.
Alexis Vuillermoz (Sojasun), Martijn Keizer (Vacansoleil-DCM), Sébastien Minard (Ag2r-La Mondiale) and Mads Christensen (Saxo-Tinkoff) were involved in the break of the day, the quartet escaping shortly after the start of the 170km stage in Châtel-Guyon.
They built up a lead of 2:15 after 15km which quickly grew to over four minutes as they crossed two climbs, and they still had a 4:10 advantage with 56km to go.
But Cannondale lead the peloton and their advantage was quickly reduced and the escapees were caught with 22km to go.
The race splintered on the climb and groups formed on the descent. Team Sky's Vasili Kiryienka was one who was prepared to take risks in the hazardous conditions but he went over his handlebars whilst leading the stage with Grivko.
BMC were chasing hard but the leading septet held on with a group of around 25 riders crossing the line, seven seconds behind Talansky.
"Anderew and the team did a fantastic job today and met our objective of getting Andrew in a good position going into the final climb," said Garmin-Sharp sports director Geert Van Bondt. "Taking the leader's jersey was a great bonus, we're happy and proud and looking forward to the coming stages."