Sebastien Ogier stayed out of trouble on day two on the Monte Carlo Rally to lead Jari-Matti Latvala by one minute 45.4 seconds going into Saturday's stages.
The Frenchman had trailed the returning Sebastien Loeb by 13.3secs ahead of the six stages on Friday, but he was able to open up a commanding lead after Loeb suffered on the day's final test.
A mistake on SS8 saw Loeb slip on an icy section of the route and badly damage his rear suspension, leaving his chances of victory hanging by a thread as he limped to the finish over 10 minutes behind.
The day had started so well for Loeb - who accepted an invite from Citroen to compete in the event - as he took SS3 by 15 seconds from his rival to hold a 28.3secs advantage, however he slowly saw that disappear as Ogier stepped up the pressure.
After Robert Kubica had taken SS4 and SS5, Loeb returned to the top of the timesheets in SS6 but his earlier lead had dwindled to just 6.6secs.
Kubica took his third stage of the day in SS7 by 1.3secs from Ogier, while Loeb could only record the fifth fastest time.
That handed Ogier the overall lead for the first time, and the defending champion exerted his dominance on SS8 with his only stage win of the day, the Volkswagen driver crossing the line 14.7secs ahead of Sebastien Chardonnet.
However, it was Loeb's accident that pushed Ogier clear at the top, with Latvala his nearest competition and Andreas Mikkelsen (+2:34.8) completing a top three for Volkswagen.
Loeb's miserable end to the day saw him drop to 15th overall, and he will need to perform superbly in the remaining seven stages if he wants to challenge for the rally win.
Meanwhile, Kubica's impressive day ended in misery as he suffered electrical problems in SS8 and lost a further four minutes.