Lefebvre started the day 24.5sec adrift of Eric Camilli’s similar Citroën C3 Rally2 car, but moved to second behind Andreas Mikkelsen when the early leader retired after going off the road and damaging his front suspension.
The former Citroën factory driver hacked a massive 14.5sec from Mikkelsen’s advantage during the first pass of Val-de-Chavagne / Entrevaux before going another 8.0sec quicker than his rival when it was repeated as the final stage.
The last-minute charge enabled Lefebvre to move in front and he arrived back to the Monaco service park 8.0sec ahead of Mikkelsen.
"I love these tricky conditions - they are like my home conditions,” beamed the Frenchman.
“I took some risks in the last stage and it's good to finish like this. I am really happy to finish the day with this rhythm," he added.
Škoda Fabia Rally2 star Mikkelsen was disappointed to drop a position and put the time loss down to a miscommunication with his safety note crew.
“I had information in my pace notes that there was a lot of ice, but in the end there was nothing and I braked too much in a lot of places," he explained.
Yohan Rossel had a much better run after improving his C3’s set-up following Thursday night’s stages. He ended 17.7sec down on Mikkelsen but had 49.8sec in hand over Marco Bulacia, who also led the WRC2 Junior category with another Toksport Škoda.
M-Sport Ford Fiesta Rally2 man Erik Cais maintained a consistent pace to finish 32.9sec behind Bulacia, whilst Grégoire Munster rounded off the leaderboard in sixth. The 23-year-old trailed the leaders by 2min 13.0sec in a Hyundai i20 N Rally2.
- Full coverage from Rallye Monte-Carlo is available on WRC+ All Live here, including every stage broadcast as it happens as well as key interviews, features and expert analysis from the service park.