Sunday has only one, 21.19km, Power Stage remaining with the rally shortened due to an unusually mild winter and a lack of snow.
Evans, in only his second rally for Toyota after switching from M-Sport Ford for this season, started the day 8.5 seconds ahead of Hyundai's Tanak.
He ended the leg with a 17.2 sec advantage after winning three of the four stages.
"Hopefully we can find the same rhythm as the last two days," said the Welshman of Sunday's final stage.
"We need to hit the nail on the head, it's a long stage and you can easily lose a lot of time if you don't gel with the conditions."
Toyota team mate Sebastien Ogier was third, moving up from fourth but 28.8 sec off the pace, with Hyundai's championship leader Thierry Neuville in sixth after winning the last stage of the day. (Reporting by Alan Baldwin in London Editing by Ian Chadband)