Almost traditionally, the Swiss WorldTour race started with a prologue. In sunny conditions, the riders were subjected to the first of many challenges over the next six days. Sepp Kuss was Team Jumbo-Visma's first rider to start in the streets of Lausanne. The American finished about half a minute behind the day's winner. Gijs Leemreize, Timo Roosen, Robert Gesink, Michel Hessmann and Steven Kruijswijk all had similar times.

Dennis started his prologue just after five o'clock. The Australian knew what he had to do. Shortly before, Hayter had clocked a fast time. Dennis' split times were similar to the Briton's throughout the stage, but he finished just under four seconds behind the winner. With an average speed of around 52 kilometres per hour, Dennis and Hayter were the only two riders to record a time under six minutes.

"I have to be satisfied with my race", Dennis said. "Of course I would have preferred to win but I can't blame myself and I gave everything. Today one rider was stronger. Hats off to Ethan. I didn't take the last corners well. I gave everything in the first few kilometres. I was a little dizzy at the end of the prologue, but I think Ethan was hard to beat today. The form for the rest of this tour is definitely there", Dennis looked ahead.