Chris Froome still in control with three stages left in the Tour de France.

COL D’IZOARD, France — On the highest mountain-top finish of the 104th Tour de France, in a rocky moonscape where the air thins, only the hardiest organisms — pine trees, tough old grasses and stubborn flowers — survive. You can add Chris Froome to that list.

Putting one hand on what would be his third consecutive Tour crown and fourth overall since his first victory in 2013, Froome emerged from the Alps on Thursday with the yellow jersey firmly on his shoulders. Having chewed his way through nearly 2,000 miles of French roads, just three stages now stand between him and top spot on the Champs-Elysees podium in Paris on Sunday. And one of those is a time trial, a discipline he excels in.

With opportunities to dethrone the three-time champion quickly running out, French rider Romain Bardet and his AG2R team again put pedal to the metal and tried to make Froome crack on the last huge climb this year, piling on the pace up the punishing Col d’Izoard — the culmination of Thursday’s Stage 18 and one of the toughest tests in a three-week race that has produced surprises aplenty.

Fending off Bardet’s attacks, and putting in a strong one of his own that initially rattled yet didn’t shake off the sturdy Frenchman, he preserved a cushion of 23 seconds overall that, unless disaster strikes in the shape of a crash or other misfortune, should be enough for victory.

French rider Warren Barguil triumphed on the Izoard’s barren slopes, winning his second stage of the tour after he attacked with four miles left to climb to the top. He also won Stage 13 last Friday.

Barguil gradually reeled in riders ahead of him on the hairpin bends and steep road — the last being John Darwin Atapuma of Colombia, with about a mile left to the finish, at an altitude of 7,743 feet.

He is now guaranteed to win the polka-dot jersey awarded for points collected during the Tour on climbs.

Froome’s lead, while far smaller than at the same stage in the Tours he won in 2013, 2015 and 2016, is sufficient for him not to have to take unnecessary risks on the twisting and technical time-trial course in Marseille on Saturday. His Team Sky should also be strong enough to control the race on Friday’s stage out of the Alps through Provence, which isn’t tough enough to provoke a big shake-up in the standings. And Sunday’s ride into Paris is traditionally a procession before only the sprinters contest victory at the end.