The 2019 world champion won four of the six stages to open up a 58.3s advantage aboard his Ford Puma, having started the day with a 4.2s margin over Suninen.
An inspired tyre call across the morning loop helped Tanak increase his lead to 47.8s, before a masterclass in tyre management maintained his momentum in the afternoon.
Hyundai’s Thierry Neuville ended the day in third (+1m03.0s) after surviving a couple of wild moments. The Belgian had 10.7s in hand over Toyota’s Elfyn Evans, who dropped from second to fourth after Toyota’s tyre strategy miscue in the morning.
Championship leader Kalle Rovanpera headed to service in fifth (+2m24.0s) after he too lost time to Toyota’s tyre mistake, before being delayed by Gregoire Munster’s dust in stage 12. The third Toyota driven by Takamoto Katsuta completed the loop in sixth (+4m07.2s).
Following a dramatic morning dominated by tyre strategy, thanks to Chile’s abrasive gravel roads, a much more conservative approach was taken for the afternoon.
The leading Rally1 and Rally2 crews opted for hard compound tyres after Toyota’s call to run softs backfired, but tyre management across the 77km loop was still a key concern.
Rovanpera set the pace on stage 10, a repeat of the Chivilingo test he won in the morning. The Finn was 2.5s faster than title rival Evans, but he was already concerned by his rubber management.
After losing almost a minute on stage nine, Evans began his recovery by taking time out of Neuville, who was also wary of the energy he'd taken out of his Pirellis. The Welshman brought the gap to third overall down to 11.3s.
Rally leader Tanak was also struggling to know how hard to push as he dropped 14.5s in the stage, although his overall lead was only reduced to 41.7s over Suninen.
“It's so difficult to understand if it's too much or how it is, it feels so, so bad,” said Tanak. “We still need to make sure we get through the loop.”
The worries over tyres came to the fore in stage 11 (Rio Lia 21.09km), when Katsuta revealed that he had suffered a delaminated tyre in this test and the previous one. The Japanese was however the only driver to suffer this issue.
At the front, Tanak pushed harder on this test having realised he’d backed off too much in stage 10. A sixth stage win pushed his overall lead over Suninen back out to 44.5s ahead of the day's final test.
Suninen was 2.8s adrift of the Ford, but faster than Evans and Neuville who were locked in a battle for third overall. Evans was neat and tidy through the test as he chipped away another 5.6s to close to within 5.7s of the final podium spot.
Neuville was however fortunate to survive a scare when his i20N slid wide into a ditch at a right-hander, cocking a front-left wheel in the process.
The Maria de las Cruces stage, which changed the complexion of the rally in the morning, once again delivered drama. M-Sport Rally debutant Munster clipped a bank twice causing punctures to his front and rear right tyres, which cost him seven minutes to rectify.
Munster, who was occupying seventh before the incident, rejoined but was caught by Rovanpera. The championship leader lost 41.3s as he battled poor visibility from the rooster trails of dust being kicked up by the Puma.
“It's a bit like driving in Super Mario kart when someone is throwing bananas or smoke bombs in front of you,” said Rovanpera. “I was definitely losing a lot of time, let's see how much we get back.”
Further down the road, Neuville was lucky to save another wild slide before revealing that he had an issue starting his i20N that was also battling a hybrid issue. He was still able to post the second fastest time, but couldn’t touch Tanak who marched to a seventh stage win by 7.8s.
Evans meanwhile lost ground in his pursuit of third-placed Neuville, ceding five seconds to the Hyundai driver.
Oliver Solberg ended Saturday with the WRC2 lead sitting seventh overall, ahead of Toksport team-mates Gus Greensmith and Sami Pajari.
Rally Chile will conclude on Sunday after a further four stages, comprising 54.12 kilometres.
UPDATE: Munster and co-driver Louis Louka were handed a 500 euro fine for holding up Rovanpera in stage 12. Rovanpera has been handed a notional time leaving him 2m02.2s adrift of the lead.
