BAGNERES-DE-BIGORRE, France -- The mighty mountains of the Pyrenees offered at least two important insights about Tour de France leader Chris Froome: He can land terrible blows to his rivals with his grinding uphill speed and can take their punches, too. In short, if the Briton in the yellow jersey perhaps isn't unbeatable, he seems very close to it.

After nine hectic days of racing over 1,513 kilometers (940 miles), the Tour luxuriates in its first rest day Monday. The pause allows the contenders for victory in Paris on July 21 to lick their wounds and regroup after Froome knocked them dizzy and grabbed the race lead with a triumphant first day of climbing in the Pyrenees on Saturday. But they'll also be ruing the opportunity they collectively wasted the very next day on Sunday to hurt Froome right back.

On what might well prove to have been one of the toughest and decisive days of this 100th Tour, and certainly one of the most tactical and interesting, Froome's rivals isolated him from his Sky teammates and forced him to ride alone -- one man against many -- up four consecutive climbs as jagged as sharks' teeth. But they could not make Froome crack.

"That was one of the hardest days that I've ever had on a bike," the 2012 Tour runner-up said after defending his yellow jersey.

The rival who harassed Froome most, with successive squirts of acceleration on the last climb, was Nairo Quintana. The lesson the Colombian drew from this drama amid pine forests and peaks with stubborn patches of snow was: "That we can break down his team a little, but that he can defend himself and is very strong."

Alejandro Valverde moved up to second overall. But his deficit to Froome remained unchanged: 1 minute, 25 seconds.

Bauke Mollema and Laurens Ten Dam, both from the Netherlands, are 1:44 and 1:50 behind Froome, respectively.