The 23-year-old Milram rider was one second ahead of American Levi Leipheimer and two seconds clear of fellow German Andreas Kloden, both Tour de France specialists from the RadioShack team.

British sprinter Mark Cavendish finished seventh in the 3.6-km time trial along Lloret de Mar's rain-soaked seafront but compatriot Bradley Wiggins did not start because of illness.

A professional since 2007, Voss said he was surprised by his win.

"I had no idea I could do it," he told reporters. "I took a lot of risks on a very dangerous descent ... and that probably made the difference.

"The rest of the time I was just riding flat out and hoping I'd do well." Voss said he had given no thought to how he would defend the leader's jersey on Tuesday's tough 182-km stage from Salt to Banyoles.

"It's the first victory of my career and I just want to enjoy the feeling that I'm the leader," he said. "We'll take it day by day."

Team Sky rider Wiggins went down with a stomach upset in the build-up to the event.

"It's a pity because he was looking forward to it and this stage in particular was perfect for him," Sky official Rod Ellingworth told Reuters.

"But things like this always happen at some point in a rider's season and better it's now than a week before the Tour de France."

The Tour of Catalunya finishes in Montmelo on Sunday.