British rider Geraint Thomas won the first summit finish of the Tour de France and claimed the yellow jersey on Wednesday with Team Sky asserting its dominance.
Four-time champion Chris Froome moved up to second overall, 1 minute, 25 seconds behind Thomas, his teammate.
Thomas attacked on the last of four climbs over the short but grueling 11th stage and finished 20 seconds ahead of Tom Dumoulin, who moved up to third overall, 1:44 behind.
Froome crossed third, just behind Dumoulin.
Greg Van Avermaet, who had worn the yellow jersey since his BMC squad won the team time trial in Stage 3, lost contact midway through the stage and finished far behind.
It was Thomas' second career stage win at the Tour, having claimed the individual time trial that opened last year's race.
Froome is attempting to match the record of five Tour victories shared by Jacques Anquetil, Eddy Merckx, Bernard Hinault and Miguel Indurain.