Mads Ostberg grabbed the Rally of Portugal lead from Sebastien Ogier at the end of stage two on Friday morning.
Ogier had already looked capable of delivering a third straight dominant win when he came through the opening Mu stage four seconds clear of nearest rival Ostberg.
Friday's five stages take place without a full service, so drivers must stick to one tyre compound all day.
Ogier chose softs all round, in contrast to most rivals, who felt the increasing temperatures would hurt the softer rubber.
Ostberg outpaced Ogier by 7s on stage two, Ourique, to move into a 3.9s lead. The Frenchman remained confident his strategy was on course, though, while Ostberg - who inherited victory on this event last year when Mikko Hirvonen was disqualified - admitted he was pushing beyond his comfort zone in places.
Qualifying pacesetter Dani Sordo was only fifth after Mu, but jumped to third on Ourique, ahead of Citroen team-mate Hirvonen and a confidence-lacking Jari-Matti Latvala in the second VW.
Ostberg's M-Sport Ford team-mates Thierry Neuville and Evgeny Novikov are presently sixth and seventh, followed by VW's debutant Andreas Mikkelsen.
Robert Kubica meanwhile holds fourth place on his debut in WRC2.
The Pole's Citroen is 22s behind class leader Esapekka Lappi's Skoda, with Sepp Wiegand and Elfyn Evans separating them.
Kubica, who is 40s clear of the rest of the WRC2 pack, lost time near the end of stage two as he reached the finish with a front tyre off the rim and a radiator leak.
Leading positions after SS2: Pos Driver Team/Car Time/Gap 1. Mads Ostberg M-Sport Ford 23m23.1s 2. Sebastien Ogier Volkswagen + 3.9s 3. Dani Sordo Citroen + 10.3s 4. Mikko Hirvonen Citroen + 16.5s 5. Jari-Matti Latvala Volkswagen + 27.1s 6. Thierry Neuville M-Sport Ford + 42.2s 7. Evgeny Novikov M-Sport Ford + 55.7s 8. Andreas Mikkelsen Volkswagen + 1m03.2s 9. Michal Kosciuszko Italia Mini + 1m15.0s 10. Martin Prokop Czech Ford + 1m23.3s