BMC rider Greg van Avermaet said his main aim was to help teammates Richie Porte or Tejay Van Garderen try to win the Tour de France after taking out stage five by more than five minutes.
The 31-year-old was part of an early breakaway and held on in the first mountain stage up the Col du Perthus to take his second Tour stage success and also capture the yellow jersey from Peter Sagan.
The Belgian leads Frenchman Julian Alaphilippe by 5min 11sec with van Garderen, Nairo Quintana and defending champion Chris Froome a further six seconds back and ready to pounce as the Tour progresses.
Van Avermaet was happy with his stage win but his attention was now on aiding his teammates.
"It's special for me," he said.
"It's the best jersey in the world.
"It's my first time and perhaps the last, so I will enjoy every moment.
"It's the best moment of my career.
"The main goal for us is having Tejay or Richie Porte on the podium in Paris."
Quintana, who has finished second to Froome twice on the Tour, tried to attack the Brit in the last few kilometres of the stage, but Team Sky responded each time to keep Froome in touch.
Movistar did see one of its Tour chances slip off the pace, with Vincenzo Nibali falling 14min 6sec behind the leader.
Peter Sagan, who held yellow for the previous two stages, also dropped back as van Avermaet stormed home on his own, 2min 34sec ahead of fellow Belgian Thomas de Gendt in second.
"We're happy to stay out of trouble," Froome said.
"The big general classification days are still to come.
"This day wasn't going to be a big showdown between the contenders."
Two-time winner Alberto Contador appeared to show the effects of two falls in the first two stages, slipping six and a half minutes behind the yellow jersey holder.
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