Overnight leader Gryazin’s hopes of a second victory of the year lasted just 9.9km into Saturday’s opening stage when the Bulgarian rolled heavily, with flames subsequently appearing beneath the bonnet of his Ypsilon Rally2 HF Integrale.
Gryazin and co-driver Konstantin Aleksandrov were able to extinguish the fire, but the incident brought an abrupt end to their day.
It opened the door for Rossel, who immediately seized his opportunity. The Frenchman was 12.5sec faster than anybody else through the opening Pelún test, vaulting from third into the WRC2 lead with a 6.7sec advantage over Robert Virves.
That set the tone for a commanding performance. Rossel won all six of Saturday’s stages and reached the overnight halt with a 58.0sec cushion over Virves.
Virves, meanwhile, remains firmly on course to secure the WRC2 Challenger title on Sunday. The Škoda Fabia RS Rally2 driver holds second place and is 33.8sec clear of third-placed Gus Greensmith.
Greensmith had been locked in a close fight with Virves’ Toksport team-mate Taylor Gill before the Australian suffered a tyre delamination on the penultimate stage of the day, costing him more than 30sec.
Despite that setback, Gill retained fourth overall and remains well placed to capitalise should any of the leading trio encounter trouble on Sunday. He finished Saturday more than three minutes clear of home hero Jorge Martínez, who in turn holds a 42.3sec advantage over fellow Chilean Alberto Heller.
Fresh from victory in Paraguay, Diego Domínguez has struggled to rediscover the same winning rhythm in Chile. The Paraguayan ends Saturday seventh, more than four minutes behind Rossel but only 12.3sec adrift of Heller, setting up an intriguing fight for sixth on the final day.