Daniel Martinez scored a first Tour de France stage win for US team Education First on Friday as Slovenia's Primoz Roglic extended his lead at the top of the overall standings after a titanic mountain struggle.
Defending champion Egan Bernal dropped time over the final kilometre of the 13th stage while Colombia's Nairo Quintana and Frenchman Romain Bardet also fell further behind Roglic.
As the race hit a nine-percent incline on the day's sixth and final climb Roglic and Pogacar managed to drop an elite clique of riders in the running to win the 2020 Tour.
Bernal now looks under severe pressure from Vuelta a Espana champion Roglic, who has a powerful team around him.
Bernal's team Ineos said their 23-year-old leader was improving each day from a bad back.
"We will do better on the really tough stages," Ineos director Benjamin Rasch said.
The holder of the green jersey, Irishman Sam Bennett, and the vastly experienced Peter Sagan will likely renew their struggle for sprint points on Saturday's 194-kilometre run over five small hills between Clermont-Ferrand and Lyon.