Britain's Jonathan Dibben secured his first victory on the World Tour circuit by winning stage six of the Tour of California.
The Team Sky rider, 23, surprised the field on the 24-kilometre time-trial around Big Bear Lake with a four-second victory over American Brent Bookwalter.
Dibben, in his first year with Team Sky, won in 28 minutes and 27 seconds.
"When I crossed the line I didn't know I'd set the fastest time for a couple of minutes," he told Team Sky.
"I guess I'd have been happy with a top 20 so to win is pretty good."
New Zealand's George Bennett goes into Saturday's seventh and final stage with a 35-second overall lead on Poland's Rafal Majka.