Swiss rider Marlen Reusser won the women's Tour de France fourth stage on Wednesday as Dutchwoman Marianne Vos retained the overall leader's yellow jersey in fifth place.
Reusser, 30, broke away with 15km left after four gravel sections in the Champagne wine region with Evita Muzic in second place and Belarussian Alena Amialiusik in third.
The 35-year-old Vos, who took over the yellow jersey with victory in stage two on Monday keeps a 16sec advantage over her closest rivals in Italian Silvia Persico and Pole Katarzyna Niewiadoma.
Ths is the longest edition of the women's Tour, after Amaury Sports Organisation, who run the men's race, started with a one-stage event in 2014.
During the dust-filled gravel sections which passed through the world-renowned vineyards in eastern France the likes of Tuesday's stage winner Cecilie Uttrup Ludwig and yellow jersey contender Niewiadoma suffered punctures before rejoining the peloton.
With 15km to go, Reusser, European road time-trial champion, made an attack from a big leading bunch as the riders returned to normal roads.
Niewiadoma's Canyon-SRAM team-mate Amialiusik, racing as a neutral rider after Russia's invasion of Ukraine earlier this year, then followed the Swiss as the group broke up.
Frenchwoman Muzic, aged just 23, completed the breakaway.
Reusser claimed the three-second bonus atop Cote des Bergers with less than 10km to go and was first over the final climb of the day on Cote du Val Perdu, with 5km left.
She dominated the closing stages and pointed at her team name on her dust-covered jersey then held her arms wide open as she crossed the finish line in Bar-sur-Aube.
Thursday's fifth stage is a flat 175.6km ride from Bar-le-Duc eastwards to Saint-Die-des-Vosges near the German border.
The eight-day race finishes on Sunday on La Super Planche des Belles Filles, where two-time winner Tadej Pogacar claimed stage victory during the men's Tour earlier this month.