Sky team leader Froome launched a solo attack 5km from the race’s first summit finish at Ax-Trois-Domaines and crossed the finish line 51sec ahead of Australian teammate Richie Porte to underline his overall victory credentials.
Spain’s two-time runner-up Alberto Contador finished over a minute behind while the victory hopes of 2011 champion Cadel Evans all but faded on an epic eighth stage.
Froome, last year’s runner-up behind teammate Bradley Wiggins, now tops the general classification with a 51sec lead over Australian teammate Porte, with Spain’s Alejandro Valverde (Movistar) in third at 1min 25sec.
Contador (Saxo) is 1:51 off the pace while Australian Evans (BMC) is nearly five minutes adrift after finishing the stage 4:12 down on Froome.
Porte, the last rider in Sky’s impressive line-up to set the pace on the 7.8 km climb to the Pyrenean ski station, said the order to hit full gas came from Froome after the Kenyan-born rider had realised Contador was in trouble.
“I’m finished (exhausted), but it was an absolutely incredible ride.”