The Tour de France yellow jersey holder had ridden with the likes of Richie Porte (BMC) and Nairo Quintana (Movistar) on his wheel all day and wanted to see what reaction he would get if he pretended to go off the front near the top of the climb.
"I just wanted to see exactly what the state of play was, to see what reaction I'd get, to see who would be looking to follow me.
"It was interesting to see Nairo was on my wheel and that he was able to follow me quite quickly. It was just to get an idea to see who might make a move over the top."
Froome has form for attacking over the top of a climb in this race, having sped off the front and holding his advantage on the Col de Peyresourde in the Pyrénées on stage eight.
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