Martin rode the 27km time trial at over 30mph
German Tony Martin beat Britain's Bradley Wiggins in Friday's sixth stage of the Paris-Nice race, to take the overall leader's yellow jersey.
With two stages remaining, Wiggins moved up to third overall, 39 seconds behind HTC-Highroad rider Martin, 25.
Martin rode the 27km time trial at an average of 30.14 miles per hour, with Team Sky rider Wiggins 20 seconds back.
"Sometimes you get beaten by a better bike rider. Tony Martin, congrats mate," Wiggins said on Twitter.
Martin now leads compatriot Andreas Kloeden by 36 seconds in the overall standings, with Wiggins third.
The riders face a hilly 215km stage from Brignoles to Biot-Sophia Antipolis on Saturday before the race concludes around Nice on Sunday.
"Paris-Nice is one of the first races I've started where I've been one of the favourites, so to show that I can handle that responsibility is important," said Martin.
"This is one of my best ever victories, especially since I've taken the race lead. It's still early in the season, but it gives me confidence for the races coming up, and for the Tour de France.
"Now, we have two tough days up ahead of us but I'm sure the boys will be up to the job, and I have quite a significant advantage. I think I can keep the jersey all the way to the finish."
BBC Sport spends day at the track with Wiggins