SAINT-MICHEL-DE-MAURIENNE, France -- One big Alpine stage completed, just two more to go, and Julian Alaphilippe is still in yellow with France yet another step closer to having a first Tour winner since 1985.

Continuing to contribute more than anyone to making this the most exciting Tour de France in decades, the French rider recovered from a moment of weakness on the lunar-landscaped Galibier pass and sped down treacherous hairpin bends on the other side to preserve his race lead Thursday.

But it wasn't a perfect day for Alaphilippe. With a decisive, well-placed attack on the slopes of the Galibier -- the last of three climbs to above 2,000 metres (6,500 feet) on Stage 18 -- Colombian rider Egan Bernal got away from Alaphilippe and ate into his lead.

Bernal vaulted from fifth to second in the overall standings. Having started the day 2 minutes, 2 seconds behind Alaphilippe, Bernal is now just 90 seconds behind him.

Bernal's teammate, defending champion Geraint Thomas, tried to make it a one-two punch by also attacking on the last hairpins leading to the top of that climb, lined by excited crowds.

But with Alaphilippe starting to wobble on the ascent, Thomas couldn't make the offensive stick. Alaphilippe caught him again on the downhill to the finish. Thomas is still 1:35 behind Alaphilippe, as he was at the start of Stage 18, but slipped back to third overall behind Ineos teammate Bernal.

Colombian rider Nairo Quintana won the first stage, flying away from everyone on the Galibier and putting some colour back into what so far had been an underwhelming Tour for the former two-time runner-up.

But it was Alaphilippe who really raised eyebrows, confounding even his own expectations in the high Alps.

Although his lead has shrunk, with the duo of Bernal and Thomas breathing down his neck, Alaphilippe is closer than ever to the podium in Paris on Sunday.

Thomas suggested that the stage simply hadn't been hard enough to make Alaphilippe crack.

"We wanted it to be hard but the pace wasn't there," he said. "The call was made for Egan to go and hopefully that would kick if off a bit, but it didn't. That's when I went as well, just to test. But at least Egan gained some time on everyone else."

Two huge obstacles lie between Alaphilippe and Paris in the shape of two more Alpine stages, both with uphill finishes.

Few had expected him to hold his own in the Pyrenees and, now, on the first day in the Alps.

But he's making believers with each extra step closer to the finish.