Reigning European Rallycross Super1600 champion Rokas Baciuska claimed a career-first fastest World Rallycross time at Loheac to lead the order on day one.
The Lithuanian, driving a Renault Megane, finished second on the road to Gronholm RX driver Toomas Heikkinen in the opening session of the weekend to set the fifth-fastest time.
He then climbed to second at the first corner in the first Q2 race, before taking the lead and race victory after the joker laps played out.
Double DTM champion Timo Scheider had made a near-perfect launch to take the lead of the same Q2 encounter but finished second in the race and on the timesheets to hold third at the end of the first day, just behind Heikkinen.
Heikkenen, who tested the GRX Hyundai for the first time at Mayenne in France on Tuesday, is making a one-off return to World RX and was fastest in Q1.
He was sixth on the Q2 timesheets, one place behind team-mate Niclas Gronholm, but remains second overnight, with Gronholm sixth.
Gronholm, who won the Norwegian round earlier in the season, led the final Q1 race but was passed by Timmy Hansen at the end of the opening lap.
Of the three drivers most likely to be fighting for the title in the final three rounds of the season, Hansen sits highest in the intermediate classification in fourth, one place ahead of Canadian round winner Andreas Bakkerud.
Hansen lost out at the first corner of his Q2 race and was only eighth fastest there, while younger brother and championship leader Kevin Hansen twice started from the outside grid slot.
He was held up in Q1 then made a better launch in Q2 to beat closest title-rival Bakkerud into Turn 1, but was hung out to dry on the outside by EKS Sport's Krisztian Szabo and ran fifth on the opening lap.
Kevin Hansen is 11th at the end of Saturday, one place ahead of Szabo and behind Anton Marklund, who battled with Bakkerud for track position in Q1.
British driver Liam Doran could not pull off a planned move around the outside at Turn 1 in his Q1 race, but made a brilliant start in Q2 to comfortably take the race lead on the opening lap and set the fourth-fastest time, putting him ninth overall.