Elfyn Evans stretched his Rally Argentina lead to 55.7 seconds with a commanding performance on Friday's second loop.
Benefiting from the soft compound of his DMACK tyres being slightly harder than Michelin's equivalent and coping better with stages that had been deluged with rain in preceding days then baked hard by the increased Friday temperatures, Evans opened the afternoon with a blistering time on the San Agustin that was 8.7s quicker than anyone else could manage.
That took the Ford driver's rally lead up to nearly 50s, and he eased back thereafter - though that still meant a shared stage win with Hayden Paddon on the following Amboy stage and then second on Santa Rosa.
Jari-Matti Latvala had ended the morning as Evans's closest rival but his afternoon went awry immediately when rising engine temperatures repeatedly put his Toyota into 'safety mode'.
Though a phone conversation with his engineers allowed Latvala to rectify the problem for the next stage, he then dropped a further half-minute with a puncture on the day's last full-length stage and fell to sixth.
Mads Ostberg was the main beneficiary and established himself in a second position he held for the rest of the day, breaking slightly clear of the rest of the podium fight on only his second appearance in his privately-entered Ford.
Latvala's troubles, Sebastien Ogier struggling with running first on the road and then bending his M-Sport Ford's steering slightly on a rock, his team-mate Ott Tanak being too cautious on SS6 then charging thereafter and Thierry Neuville pressing on after a broken damper and puncture in the morning all combined to make the battle for third ultra-tight for most of the afternoon. At one stage all four cars were within 3.7s.
They spread out a touch by the end of the day - Neuville pulling away to sit third overnight and closing to within 5s of Ostberg by winning the evening's Parque Tematico superspecial.
Ogier is 6s off Neuville and 4.6s ahead of Tanak, who lost time driving the final part of SS8 with a puncture.
Following his morning roll, Paddon became the first man to match Evans all day when he equalled his SS7-winning time and then went fastest of all on SS8. That at least brought him past Ford privateer Lorenzo Bertelli into seventh overall, though further progress will require attrition ahead.
Juho Hanninen's earlier power loss was resolved, but his recovery was very muted and he continues to chase Bertelli.
Pontus Tidemand leads the attrition-ravaged WRC2 class in 10th overall, with Dani Sordo inching back towards the points following his earlier 11-minute delay with a broken steering arm.
Citroen hopes to get both Craig Breen and Kris Meeke back in under Rally2 following their respective gearbox failure and crash on Friday but they would be classified nearly 40 minutes away from the points-scoring positions when they rejoin.