The cursed of a week spent in the cold, the wind and often on the demanding Cévennes reliefs, Mattias Skjelmose (Trek-Segafredo), second in the general classification, one second behind the winner.
The Dane had endorsed the leader's coral jersey on Saturday at Mont Bouquet by beating Powless in the sprint.
But the American, who was only four seconds behind on Sunday morning, took five seconds from him in the half-flat, half-sloping time trial from the Cévennes capital (10.7 km) to the hill of the Hermitage .
Frenchman Pierre Latour (TotalEnergies), voted the most combative rider of the event, completes the final podium 12 seconds behind the leader.
Powless succeeds the winners of the Frenchman Benjamin Thomas (Cofidis).
Like Benoît Cosnefroy in 2020, the American also achieved the opening double of the French season.
Last Sunday, he had already won the 45th Grand Prix de Marseille La Marseillaise.
He will return to the south of France in a month, for Paris-Nice.
"The Etoile de Bessèges was perfect to prepare for Paris-Nice," said the 26-year-old Calfornian.
"These are similar races, with a lot of wind and climbs."
If Skjelmose fails by anything, the Trek-Segafredo team leaves with two stage victories after the crushing domination of Pedersen on Sunday in the final time trial.
Despite the last two kilometers uphill, the powerful 2019 world champion beat the Britons of Ineos, Joshua Tarling and Ben Tulett, by eight and ten seconds respectively.
© 2023 AFP