Sebastien Ogier in control after dominant Monte Carlo Friday
Ogier, who is competing only part-time in this year's championship, won four of the day's six stages to build a 36-second buffer to Toyota team mate and reigning champion Kalle Rovanpera (22).
The Frenchman won both of Thursday's night stages and is chasing a ninth Monte Carlo win, one more than the record he shares with compatriot Sebastien Loeb (48).
Loeb, a nine-time world champion and last year's winner in Monte Carlo, is absent this time.
Toyota's Elfyn Evans (34), who had been second overnight, dropped down the order to fifth after losing 40 seconds to a puncture on stage five with Rovanpera in a tight battle with Hyundai's Thierry Neuville (34).
Ogier carried an extra spare tyre on board and said the risk of punctures meant he took things "a bit more easy" on the last stage.
"I'm just happy to bring the car home tonight," he said.
M-Sport Ford's Ott Tanak (35) was in fourth place, 16.3 seconds behind Neuville.
The rally ends on Sunday.
