Welshman Stephen Williams pulled off the biggest victory of his career by winning La Fleche Wallonne in Belgium.
The Israel-Premier Tech rider, 27, is the first British male winner of the 88-year-old spring classic.
But fellow Briton Tom Pidcock was among several riders to abandon the race amid torrential conditions in Ardennes.
“I’m so happy. I’ve watched this race so many times on television and dreamed of coming with good legs to try to win it. I’m on cloud nine,” Williams said.
“I saw the ‘300m to go’ line and I thought if I could put five seconds into the group and get near the line, then I could hold on.”
Williams came into the race on the back of victory in the Tour Down Under and a series of strong displays at the Volta a Catalunya but few predicted this surprise win.
He thrived in the rain-soaked conditions which saw several leading contenders abandon, such as Pidcock, Mattias Skjelmose and Tiesj Benoot, and only 44 riders finish.
Danish rider Soren Krach Andersen opened up an initial two-minute gap on the vastly reduced peloton.
The 124-mile (199km) course from Charleroi to Huy finished with a fourth ascent of the Mur de Huy climb, on which Williams held off Frenchman Kevin Vauquelin and Belgian Maxim van Gils.
Williams added: “I do enjoy racing this kind of weather and to come away with a victory – I’m just over the moon.
“The boys backed me all day and gave me the best chance to get a result. To come away with the win here is really special.”
Niewiadoma powers to victory
Polish rider Katarzyna Niewiadoma claimed the 19th win of her career but the first of the season by powering to victory in the women’s race.
Niewiadoma, second in the Tour of Flanders, followed a late attack by Elisa Longo Borghini on Mur de Huy to break clear of Demi Vollering who mounted a late response to finish second.
La Fleche Wallonne men’s result
1. Stephen Williams (GB/Israel-PT) 4hrs 40mins 24secs
2. Kévin Vauquelin (Fra/Arkea-B&B Hotels) same time
3. Maxim Van Gils (Bel/Lotto DSTNY) +3secs
4. Benoît Cosnefroy (Fra/Decathlon-AG2R La Mondiale)
5. Santiago Buitrago (Col/Bahrain Victorious)
La Fleche Wallonne women’s result
1. Katarzyna Niewiadoma (Pol/Canyon-SRAM) 3hrs 55mins 29secs
2. Demi Vollering (Ned/SD Worx-Protime) +2secs
3. Elisa Longo Borghini (Ita/Lidl-Trek) +4secs
4. Evita Muzic (Fra/FDJ-Suez) +7secs
5. Ashleigh Moolman-Pasio (RSA/AG-Soudal) +11secs