Strade Bianche starts and ends in Siena and features uneven gravel on Tuscany’s famous white, chalky roads, including the Monte Sante Marie section.
Pogacar made his decisive move there, just as he did two years ago, and when Seixas attacked about 18km from the finish, only Del Toro went with him, refusing to help the young French star chase down his team-mate.
Jan Christen finished just ahead of Britain’s Tom Pidcock to ensure there were three UAE riders in the top six.
“I’m super happy,” said Pogacar. “I was chasing really hard on the steepest part of the climb on Sante Marie.
“But I said to myself, ‘I will go all out to the top and then see if [Seixas] can bridge or he will make a gap’. In the end I saw that it’s enough, and I knew that Isaac and Jan [were there] also, so this helped a lot.”
In the 133km women’s race, seven riders arrived together at the Via Santa Catarina, the final climb up to the Piazza del Campo finish, and they were soon whittled down to four.
Elisa Longo Borghini led most of the way up the climb but went into the penultimate corner shoulder-to-shoulder with Franziska Koch and Katarzyna Niewiadoma, before 32-year-old Chabbey darted down the inside to claim victory ahead of Niewiadoma, with Koch finishing third.