The 6km course in Cham was well suited Dennis’s big gear power, which he appears to have retained even as he transitions to a full-time general classification rider.
Ryan Mullen (Cannondale-Drapac) was the first rider in the hot seat with a time of 6min 37sec. He waited for over two hours until he was dethroned by Dennis who bettered his time by 13.35 seconds.
Dennis crossed the finish line in 6min 24sec, with an average of 56.16 km/h, a new record in Tour de Suisse. It was his first stage win in the Swiss race and was the 10th Australian rider to do so.
Stefan Küng joined his BMC team-mate on the podium to finish second while Matthias Brändle (Trek-Segafredo) was third on the stage, nine seconds down.
"I actually thought that Stefan Kung would probably beat me,” Dennis said. “Obviously it's his home country so it would have been nice for him to win but he's got more time than me, he's younger and he's a huge talent.
“I think in a couple of years he might have the victory over me so I will take it while I can.
Among the top favourites for the general classification, Tom Dumoulin (Sunweb), fresh off this year’s Giro d’Italia victory, showed that he still carries good form by finishing 5th on the day, posting the same time as Brändle and his Australian teammate Michael Matthews, 4th fastest of the day.
This Sunday, Tour de Suisse continues with a 172.7km undulating stage in Cham, with the peloton taking on a 43.6km circuit four times.
"Stage two is a lot harder than it looks on paper,” Dennis said. “The guys were saying last time they did this circuit that there were 50 or so guys at the finish. But I'll see how my legs are.
“I’m good over a six to ten-minute effort but I haven't really even looked at tomorrow's stage too seriously. I might be really bad or I might be good and be able to keep the jersey.
“I have nine seconds over Michael Matthews and he's a good sprinter. I think it's ten seconds on the line so if he wins and I'm in the peloton, I'll lose it. It might be a day, or two or three."
"We're here for Damiano Caruso, he's our GC guy. I'm not here with GC on my mind. I'm here to have some fun and see how it goes in between the two time trials."