Australia's Luke Durbridge beat triple Olympic champion Bradley Wiggins into second place in Sunday's Criterium du Dauphine prologue in Grenoble, France.
The 21-year-old junior world time trial champion finished one second ahead of Wiggins, who is defending his title.
World time trial champion Tony Martin was fifth with Tour de France champion Cadel Evans in ninth, six seconds behind the leaders.
Monday's first stage is a 187km stage from Seyssins to Saint-Vallier.
Durbridge said: "I'm speechless. I didn't expect this at all."
Wiggins and many of the other riders are using the event as a warm-up for the Tour de France, which begins on 30 June.
The Briton told the Team Sky website afterwards he was happy to be back racing and to have registered a strong time.
"I'm happy enough to finish second but it's about the whole week. I couldn't have asked for better today," he said.
"It's always the same with prologues. With riders going three hours apart there's always different conditions. The wind changed massively today. Some guys had disadvantages on the course elsewhere at the start and also advantages.
"I'm just pleased it stayed dry really. It was perfect. I stayed safe and I'm where I want to be at the moment and I'm just trying to enjoy it."