The Estonian, bidding to extend his FIA World Rally Championship lead, ended the longest leg of the four-day asphalt event with a 32.4sec advantage in his Yaris over Kris Meeke.
Jari-Matti Latvala overcame a ragged morning to hold third, a further 9.4sec behind after a stellar day for the Japanese manufacturer.
Tänak’s delight contrasted with title rival Thierry Neuville’s heartbreak. For a second day the pair duelled at the head of the leaderboard, never split by more than a handful of seconds through the morning’s four country lane tests in Saarland.
Despite briefly stalling his engine, Neuville reached mid-leg service 5.0sec down after winning two special stages.
The daunting multi-surfaced Baumholder tank training roads were predicted to be a pivotal point of the rally and they lived up to that forecast. Neuville punctured early in the marathon 41.17km Panzerplatte test and dropped nearly 90sec stopping to replace it.
“We had a puncture on the rear left. It’s a lottery and we were really unlucky. We were in the middle of the road so I don’t know where that came from,” he said.
With the pressure removed, Tänak eased though the second pass of Baumholder, the first occasion on which he had been able to relax.
“This morning Thierry was faster than me and I didn’t want to take risks. Unfortunately he hit problems and we have a comfortable lead. Baumholder is so, so tricky so I think you need to have some luck if you are pushing and come out without punctures,” he said.
Kris Meeke moved up to take a surprise second place at the end of Saturday's stages.
Meeke and Latvala could not find a way by Sébastien Ogier, who continued to struggle with his understeering Citroën C3 in third, until the first pass through Panzerplatte. Both overhauled the Frenchman and Meeke widened the gap over his team-mate in the final test.
Dani Sordo recovered from last night’s gearbox problem to hold fourth in his i20. He was almost 25sec clear of Neuville, who lost more time in the final stage when he spun and inadvertently deactivated the gearchange system after hitting an in-car button.
Neuville still managed to overtake team-mate Andreas Mikkelsen, who ended 2.1sec behind in sixth despite twice sliding off the road. Esapekka Lappi was seventh, despite a spin and a heavy landing which cracked his C3’s windscreen.
Ogier’s day went from bad to worse when he stopped to change a puncture in the final test, losing 90sec and sinking to eighth. Gus Greensmith and Takamoto Katsuta completed the top 10, although Greensmith dropped almost three minutes after clipping a tree.