Sebastien Ogier's Monte Carlo Rally lead ballooned to more than a minute after the first two Saturday stages, despite damaging a wheel.
The reigning world champion started the day 14.9s clear but smashed his main rival Ott Tanak on a devilishly tricky 18-mile opening stage topped by Andreas Mikkelsen.
Ogier broke part of the left-rear wheel rim on his M-Sport Ford Fiesta WRC but still completed SS9 almost a minute faster than his 2017 World Rally Championship team-mate.
Tanak was quickest on the second, shorter morning stage but complained about a damper problem despite clawing back 15.5s against a conservative Ogier, whose lead stands at 1m03.4s.
Jari-Matti Latvala jumped two spots in one stage to end the morning third overall.
The Toyota driver was just 0.2s behind team-mate Esapekka Lappi after Friday's running and was on course to overhaul his fellow Finn for fourth when it emerged that third-placed Dani Sordo had stopped on the stage.
Latvala took full advantage, beating Lappi by more than half a minute on the stage to vault into a clear third as Sordo's podium challenge came to an end with his Hyundai in a ditch.
That means all three i20 WRCs have had their season openers ruined.
Sordo's woe put Thierry Neuville up to eighth as he recovers from a torrid Friday, while Mikkelsen dropped out of contention on Friday with an alternator problem.
He returned as a Rally2 runner and benefitted from a favourable road position, running after the other WRC drivers, to top SS9 despite suffering "three spins in a straightline!" and then set the second-best time on SS10.
Kris Meeke is fifth but had his advantage over Bryan Bouffier trimmed to just over half a minute after a tricky couple of stages.
Comfortable WRC2 leader Jan Kopecky is now into the top 10 thanks to Sordo's off.
Leading positions after SS10
|1||Sebastien Ogier, J.Ingrassia||M-Sport Ford WRT||Ford||2h45m21.2s|
|2||Ott Tanak, M.Jarveoja||Toyota Gazoo Racing WRT||Toyota||1m03.4s|
|3||Jari-Matti Latvala, M.Anttila||Toyota Gazoo Racing WRT||Toyota||1m41.1s|
|4||Esapekka Lappi, J.Ferm||Toyota Gazoo Racing WRT||Toyota||2m06.6s|
|5||Kris Meeke, P.Nagle||Citroen Total Abu Dhabi WRT||Citroen||4m29.8s|
|6||Bryan Bouffier, X.Panseri||M-Sport Ford WRT||Ford||5m02.6s|
|7||Elfyn Evans, D.Barritt||M-Sport Ford WRT||Ford||5m18.8s|
|8||Thierry Neuville, N.Gilsoul||Hyundai Shell Mobis WRT||Hyundai||5m48.9s|
|9||Craig Breen, S.Martin||Citroen Total Abu Dhabi WRT||Citroen||8m37.1s|
|10||Jan Kopecky, P.Dresler||Skoda Motorsport II||Skoda||11m09.8s|
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