ANNECY, France (AP) — Chris Froome believes the mountains will reveal the true Tour de France contenders as he looks forward to the first of three grueling stages in the Alps.

"I'm feeling good and optimistic about the upcoming stages," the four-time champion said on Monday, the Tour's first rest day.

Froome, who is eighth overall after nine stages, is 1 minute, 42 seconds behind yellow-jersey holder Greg Van Avermaet before the first Alpine stage on Tuesday.

Van Avermaet is not expected to be a threat in the mountains, and Froome suggested the Belgian "will find it difficult to hang on tomorrow. It's a proper climbers stage."

After an opening week of relatively flat routes, the first significant ascents begin with four categorized climbs as well as the punishing Montee du plateau des Gileres, which features a six-kilometer climb at an incline of 11.2 percent.

"It's a tough stage. It will definitely start shaping the GC," Froome said of the general classification.

Sky teammate Geraint Thomas is second overall, 0:43 behind Van Avermaet, meaning the team has two viable options to claim the yellow jersey over the second week of the three-week Tour.

"It's great for us to have those options to play when it comes down to it, especially looking at some of our rivals who have got two or three options in their team," Froome said.

"The team around us is such a capable group of guys, and we're really going to be coming into our element now in the mountains."