Place was the top seed after posting the fastest time in qualification, but made a sluggish start in the final as Fiva moved to the front with local hero Erik Mobärg in second.
Britain's Oliver Davies was in fourth, but he was still in with a chance approaching the closing jumps.
In a thrilling finish, Fiva repelled first Mobärg and then the fast-finishing Place to secure his first ever world title having been overall World Cup champion in 2012/13.
Näslund flew out of the gates with Smith and France's Alizee Baron chasing her while another Swiss, Talina Gantenbein, toiled in fourth.
The Swede, who was world champion back in 2017 in Sierra Nevada, managed to establish something of a gap as Smith and Baron battled it out for second.
Smith challenged for the lead but then somehow managed to stay upright on a right-hand bend, and it was another close finish with Näslund winning from Smith and Baron.
Want to fin out how Smith got ready for this season? Here we go.