Kerbaol (Ceratizit-WNT) broke clear on the descent of the day's final climb with 15km to go, opening up a gap that proved decisive, winning by 21 seconds from the pursuing group.
Her daring ride lifted her to second in the general classification, 16 seconds behind yellow jersey wearer Katarzyna Niewiadoma who took the lead on the previous stage following a crash involving then-leader Demi Vollering.
Dutch great Marianne Vos sprinted to second on the stage to take over the green jersey.
Saturday's 164-km stage features five categorised climbs.