After Tadej Pogačar cruelly stole victory from him on the line in Laruns despite spending some 60 kilometres in the lead on Stage 9, Team Sunweb went all in for their young charge Hirschi.
43 kilometres from the finish Sunweb's Tiesj Benoot and Søren Kragh Andersen jumped from the bunch and passed the remnants of an early escape. When Hirschi bridged with several other riders, they played the perfect foil when he marched away up the final climb 28kms from the finish, as they looked to frustrate a bridging Julian Alaphilippe.
For good measure, Nicolas Roche later joined his teammates, all of them refusing to collaborate as the race blew up in the wake of the Swiss rider as he put on another descending masterclass.
While the victory is sweet revenge after two podium finishes this Tour de France, Hirschi said he wouldn't have won today (Friday AEST) without his long-range attack on Stage 9.
"Unbelievable," Hirschi said after the stage. "Today I had never believed I could make it. I was doubtful. I went full gas.
"My first pro victory and at the Tour, it couldn't be better.
"It's like a dream. I don't know it's just nice."
"Laruns gave me a lot of confidence otherwise I never would have attacked on the climb."
"It gives me the extra power, podiuming twice on the road."
Earlier, Imanol Erviti (Movistar), Max Walscheid (NTT), Luis Leon Sanchez (Astana) and Nils Politt (Israel Start-Up Nation) broke off from the active bunch after 8kms raced and multiple attempts from riders like Peter Sagan, Matteo Trentin and Mads Pedersen to make a break.
But with the quartet posing no threat to the yellow or green jersey, Deceuninck-Quick Step and Jumbo-Visma ultimately allowed them some breathing space, the leaders gaining over a minute and a half advantage by the time Mathieu Burgaudeau (Total Direct Energie) jumped from the peloton at 26kms in search of the leaders.
Kasper Asgreen (Deceuninck-Quick Step) joined the Frenchman a kilometre later and they hovered in limbo one minute behind the break until hooking up with the leaders after the intermediate sprint at 66kms.
With the break securing the first six set of points at the intermediate sprint, Sam Bennett and his Deceuninck-Quick Step pilot fish Michael Mørkøv ensured Peter Sagan was only left with seven points as the Irishman moved 70 points clear of Sagan crossing the line two places ahead.
BORA-hansgrohe, however, didn't allow the break too much leeway, hoping to get Sagan up for the 50 points maximum at the finish or Maximilian Schachmann for a stage win. They upped the pace on the category 3 Cote de la Croix du Pey climb which dropped the green jersey Sam Bennett and swallowed up most of the breakaway.
After Movistar's Marc Soler joined them a few hundred metres later, the Spaniard then attacked solo with 40kms but was soon reeled back in by Benoot and Søren Kragh Andersen and they were all soon joined by Schachmann, Hirschi, and Quentin Pacher (B&B Hotels-Vital Concept). Hirschi counterattacked another move from Soler, soloing away himself up the category 2 Suc au May.
A counter-attacking group formed behind and included Bob Jungels (Deceuninck-Quick Step), Alessandro de Marchi (CCC Team), Alexey Lutsenko (Astana Pro Team), Pello Bilbao (Bahrain-McLaren), Jesús Herrada (Cofidis), Michael Gogl (NTT Pro Cycling), Kenny Elissonde, Jasper Stuyven (Trek-Segafredo), Sébastian Reichenbach (Groupama-FDJ) and Pierre Rolland (B&B Hotels-Vital Concept).
Alaphilippe bridged to this group and then attacked up Suc au May to join the pursuing group behind Hirschi. But with his Sunweb teammates still in this group serving as virtual anchors, Hirschi's victory was all but assured with 47 seconds in hand, further cemented as Alaphilippe had a mechanical in the final three kilometres.
The 2020 Tour de France continues with Stage 13, a 191km day in the mountains of the Massif Central, from Châtel-Guyon to Puy Mary Cantal. Watch the race on the SBS ŠKODA Tour Tracker and SBS On Demand from 7:40pm AEST, with television coverage starting from 9.30 AEST on SBS HD.