Slind, who last weekend ran both the WC three-mile and the Vasaloppet, was first into the race but was passed by Ragnhild Haga on the very last stretch while Diggins finished third.
It was 32-year-old Hagas, Olympic champion in 10 km free in 2018, first individual victory in the World Cup ever.
Moa Illar had superior skis and skied away from all the other downhills.
At the ski change halfway after 24.9 km, the Swede was first and brought the German Victoria Carl with her while the rest of the field changed skis.
Ilar had a gap to Jessie Diggins of 17.6 who was out third.
During yesterday, the Swedish advance favorites Ebba Andersson and Frida Karlsson had to withdraw their bids due to a cold.