The Jumbo-Visma rider, who had finished third in the previous two editions, attacked in the final 13km of the 184km race, crossing the line alone on Siena's historic Piazza del Campo.

Italy's Davide Formolo of UAE Emirates was 30 seconds behind with Germany's Maximilian Schachmann, a further two seconds adrift in third, after nearly five hours in the saddle with temperatures hitting the high 30s Celsius.

"Over the last two editions of Strade Bianche, I gained a lot of confidence," said Van Aert.

"It's never easy to win and it was harder than usual in today's circumstances.

"It makes the win even better. This is proof that I'm at the highest level now.

"To have won Strade Bianche at the age of only 25, with a cyclocross background is a huge achievement."

Vincenzo Nibali crashed with Peter Sagan also among the many riders who failed to finish the gruelling race.

Belgian Van Aert triumphs as top cycling returns at Strade Bianche

The pack of riders pedal along a dusty gravel road during Saturday's Strade Bianche. AFP/Marco BERTORELLO


Earlier in the day, Dutch rider Annemiek van Vleuten won the women's race on the famous white dirt roads for the second year in a row.

The 37-year-old Mitchelton-Scott rider crossed 22 seconds ahead of Margarita Garcia Canellas of Ale BTC Ljubljana with the Spaniard having led for much of the 136km race through the rolling hills and white gravel roads of Tuscany.

"Piazza del Campo for me is the most beautiful place to win a race," said Van Vleuten.

"What a day full of emotions, I didn't think I could catch Mavi Garcia. It was a very spectacular race in a unique scenario."

American Leah Thomas of Equipe Paule Ka was third at 1min 53sec in the race which had originally been scheduled for March 7 but was postponed because of the coronavirus pandemic.