Ogier need score only 16 points -- effectively second place or third on the road at Sunday's finish plus a power stage point -- to continue a 12-year stranglehold by French drivers called Sebastien.
Sebastien Loeb won the championship nine years in a row for Citroen before departing and leaving the stage clear for his compatriot to dominate.
Spaniard Dani Sordo, who is not in contention for the title, won two of Friday's three afternoon stages and was leading his home rally with an advantage of 17 seconds over Ogier, who won the Spanish round in 2013 and 2014.
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Andreas Mikkelsen, Ogier's Volkswagen team mate and closest championship rival, was in third place and a further 18.1 seconds adrift.
Mikkelsen is 68 points behind Ogier while Hyundai's Belgian driver Thierry Neuville is 83 points off the lead with two races remaining after Catalunya.
A win is worth 25 points in rallying but there are also additional points available to the fastest three drivers in the final 'power stage'.
Neuville spun on the muddy gravel of the day's fifth stage and damaged his car, losing the front bumper and dropping back in fourth place overall.
Volkswagen can also secure their fourth manufacturers' championship on Sunday by scoring 20 points more than Hyundai.
(Reporting by Alan Baldwin in London, editing by Pritha Sarkar)
