France’s Benoit Cosnefroy edged out compatriot Julian Alaphilippe to win the Bretagne Classic as British duo Ethan Hayter and Connor Swift earned top-five finishes.
While world champion Alaphilippe attacked on a number of occasions, Cosnefroy held his nerve to claim his first World Tour win.
Hayter and Swift finished fourth and fifth, 13 seconds behind the victor.
Tour de France winner Tadej Pogacar was dropped with 45km remaining.
The Slovenian, racing for the first time since winning bronze at the Olympic Games in Tokyo, had to settle for 60th.
After attacking out of the bunch with 65km remaining, 25-year-old Cosnefroy held off Deceuninck-Quick-Step duo Alaphilippe and Mikkel Honore of Denmark to claim the biggest win of his career.
Bretagne Classic results
1. Benoit Cosnefroy (Fra/AG2R Citreon Team) 5hrs 59mins 56secs
2. Julian Alaphilippe (Fra/Deceuninck-Quick-Step) same time
3. Mikkel Honore (Den/Deceuninck-Quick-Step) +3secs
4. Ethan Hayter (GB/Ineos Grenadiers) +13secs
5. Connor Swift (GB/Team Arkea Samsic) same time
6. Franck Bonnamour (Fra/B&B Hotels)
7. Jasper Stuyven (Bel/Trek-Segafredo)
8. Valentin Madouas (Fra/Groupama-FDJ)
9. Quentin Pacher (Fra/B&B Hotels)
10. Giacomo Nizzolo (Ita/Qhubeka-NextHash)