ANNECY-SEMNOZ, France – Chris Froome retained his big race lead Saturday to all but ensure he will become Britain's second consecutive Tour de France champion after Bradley Wiggins.
Only an accident or other freak mishap on Sunday's largely ceremonial final ride to Paris could stop Froome from winning the 100th Tour.
Froome finished third in a dramatic Stage 20 to the ski station of Annecy-Semnoz in the Alps.
Nairo Quintana from Colombia won the stage and moved up to second overall.
Joaquim Rodriguez from Spain rode in 17 seconds behind Quintana. He moved up to third overall. Froome's lead is more than 5 minutes over both.
Alberto Contador, who had been second at the start of the day, struggled on the final climb and dropped off the podium.
The 125-kilometer (78-mile) trek was the last of four successive stages in the Alps and the final significant obstacle Froome needed to overcome before Sunday's usually relaxed ride to the finish on the Champs-Elysees in Paris.
Froome first took the race lead and the yellow jersey that goes with it on Stage 8, when he won the climb to the Ax-3 Domaines ski station in the Pyrenees.
All that remains now is Stage 21, a 133-kilometer (82-mile) ride from Versailles to the Champs-Elysees.
Saturday's stage did a big loop south of Annecy, through the mountains of Savoie between the lakes of Annecy and Bourget. This is cheese-making country, with lush Alpine pastures and dense, naturally cool forests.
Unlike on Friday, when storms drenched the pack, the sun shone and the skies were blue. When a motorbike-borne television camera focused on Spanish rider Alejandro Valverde, he motioned that riding in such conditions was hot, tiring work.
The ride took the racers up six climbs. The last two of those were particularly tough. The last steep climb to Annecy-Semnoz, past ski lifts and ski slopes, was rated HC or "Hors Categorie", meaning it's considered too hard to classify.
It was the last really tough climb of this Tour. The riders have just two small humps to climb on their leisurely Sunday ride from the Versailles Palace to the Champs-Elysees' cobbles, where sprinters including Mark Cavendish will battle for the stage win.
Uniquely for the 100th Tour, Stage 21 will set off in the late afternoon, so the race finishes more or less as the sun is setting behind the Arc de Triomphe.
For a chunk of Saturday, the race was led by its oldest rider, Jens Voigt. The 41-year-old German was part of a group of 10 riders that broke away from the pack early in the stage.
But he was caught in the battle on the final climb. Quintana, Froome and Rodriguez rode off, leaving Contador to labor behind. The winner of 2007 and '09 who was stripped of his 2010 win and banned for a failed doping test ran out of legs.
Contador placed seventh in the stage, coming in more than 2 minutes behind Quintana. That dropped him to fourth overall, more than seven minutes back from Froome.