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By Martyn Herman
UTRECHT, Netherlands, July 4 (Reuters) - Australian Rohan Dennis proved too hot to handle as the Tour de France began with a 13.8-kilometre individual time trial through the sweltering streets of Utrecht on Saturday.
One of the early starters in the 198-strong field, the BMC Racing Team rider averaged 55.446 kmh to stop the clock in 14 minutes 56 seconds to take the yellow jersey.
Germany's Tony Martin (Etixx-Quick Step) was second quickest, five seconds behind, with Swiss Fabian Cancellara, one of the favourites, a second further adrift.
Dennis's searing pace was the fastest average speed ever recorded in a Tour de France individual time trial -- surpassing Briton Chris Boardman's 1994 effort over 7km in Lille.
"I didn't expect to go that fast. I was targeting around 16 minutes," Dennis, who once held the hour record recently taken by 2012 Tour winner Bradley Wiggins, said as he watched to see if anyone could beat his time.
An estimated 700,000 people turned out to watch the opening stage as the Netherlands welcomed the Grand Depart for the sixth time, and they were not disappointed as the sport's powerhouses lit the blue touchpaper for the battles ahead.
While Dennis became the first Australian to win the opening stage of the Tour since Bradley McGee in 2003, the main contenders to be wearing the yellow jersey when it ends in Paris on July 26 avoided any mishaps on the high-speed curves.
Defending champion Vincenzo Nibali was 43 seconds slower than Dennis, Britain's Chris Froome was 50 seconds back and Spain's Alberto Contador was 58 adrift. (Editing by Mark Meadows)