Frenchman returns from Dakar Rally quest to lead old rival Ogier and Evans.
Sébastien Loeb became the oldest driver to lead an FIA World Rally Championship round after a sensational return to dominate Rallye Monte-Carlo on Friday.
As he approaches his 48th birthday, the Frenchman won four of the six French Alps speed tests to lead the first rally of the WRC's innovative new hybrid era by 9.9sec in M-Sport's Ford Puma.
The Monaco-based event is Loeb's first WRC outing for more than a year and, currently, a one-off appearance with the British squad.
Loeb was second after Thursday night's short opening leg behind old foe Sébastien Ogier. He charged by his fellow countryman in the last of the morning's three special stages and preserved his advantage in the afternoon, despite a small technical issue.
"The first four stages were really great, then we had a little hybrid problem," he explained. "In the last stage I made a good drive, but maybe it was freezing a bit more. We had some little ice coming out at the end of the stage, so it was a bit tricky.
"I was really surprised when I was doing the best time in yesterday's shakedown in the first pass. Usually in shakedown I'm not great, but with this car I was immediately in the rhythm. It's not a big gap, but I'm happy to be leading after the first full day."
Ogier dropped to third behind Toyota GR Yaris team-mate Elfyn Evans after a cautious approach on frosty roads in this morning's final stage, but fastest time on the afternoon repeat promoted him back to second.
A wary run in the same test cost Evans valuable seconds. The Welshman ended 12.1sec adrift of his colleague after a frustrating day learning the intricacies of driving with the hybrid system for the first time in competition.
Thierry Neuville topped an intense battle for fourth in a Hyundai i20 N. His day improved after an eye-opening first stage in which he described the balance as 'a nightmare'. "I've never been so scared while driving," he said.
The Belgian stiffened his car's settings and ended 8.9sec clear of team-mate Ott Tänak, with Craig Breen dropping 2.5sec behind the Estonian in the final stage in another Puma.
Team-mate Gus Greensmith celebrated his first WRC stage win en route to seventh. But for a minor problem with the hybrid system, the Briton would have been snapping on Neuville's heels.
Adrien Fourmaux was fourth overnight, but the Frenchman crashed his Puma down a ravine in the opening test. He and co-driver Alex Coria escaped injury, a testament to the new enhanced safety cell chassis introduced this year.
Today's action switches west for five stages near Digne-les-Bains. Three morning tests precede a tyre change in the town before the latter two are repeated. The day features two climbs of the mythical Col de Fontbelle, likely to feature several kilometres of snow and ice at the summit.
Leading positions after Friday
1. S Loeb / I Galmiche FRA Ford Puma 1hr 22min 49.0sec
2. S Ogier / B Veillas FRA Toyota GR Yaris +9.9sec
3. E Evans / S Martin GBR Toyota GR Yaris +22.0sec
4. T Neuville / M Wydaeghe BEL Hyundai i20 +47.8sec
5. O Tänak / M Järveoja EST Hyundai i20 +56.7sec
6. C Breen / P Nagle IRL Ford Puma +59.2sec