Jari-Matti Latvala pulled out a 17-second lead over Volkswagen team-mate Sebastien Ogier by the end of a tough first day of Rally Argentina.
The VW duo ended up swapping first place on all four of Friday's stages, with Ogier quicker on the shorter Santa Catalina stage each time, before Latvala responded on both runs through the 52 kilometres of Ascochinga.
In the afternoon, Latvala was substantially faster than his World Rally champion team-mate. Ogier had retaken the lead on Santa Catalina by half a second, but Latvala was a full 18s quicker on the longer stage as he claimed the top spot back.
But while VW still holds a one-two, its hopes of a podium sweep have been dented.
Andreas Mikkelsen was running a solid third before stopping with a mechanical problem near the end of Ascochinga. VW has already said that he will rejoin under Rally 2 rules on Saturday.
With fourth-placed Thierry Neuville's Hyundai also coming to a halt with technical issues on SS5, Kris Meeke jumped from fifth to third in the remaining Citroen.
The attrition also elevated M-Sport's cautious duo Elfyn Evans and Robert Kubica, who are now just two tenths of a second apart in fourth and fifth overall.
Both Hyundais hit trouble on Ascochinga, with Dani Sordo's car - which had been repaired after its earlier turbo troubles and was back on the pace - stopping with engine problems.
Leading positions after SS5:
Pos Driver Team/Car Time/Gap
1. Jari-Matti Latvala VW 1h57m36.3s
2. Sebastien Ogier VW +17.7s
3. Kris Meeke Citroen +1m07.4s
4. Elfyn Evans M-Sport Ford +3m48.1s
5. Robert Kubica M-Sport Ford +3m48.3s
6. Martin Prokop Czech Ford +4m12.2s
7. Nasser Al-Attiyah M-Sport Ford +5m36.8s*
8. Yuriy Protasov Ford +8m22.0s*
9. Diego Dominguez Skoda +10m36.5s*
10. Gustavo Saba Ford +11m43.0s*