Tanak headed into the afternoon stages with a 3.5s lead over part-time driver Ogier, but ended the day trailing the eight-time world champion by 17.1s.
The Estonian revealed he’d received a team order to back off with the manufacturer’s championship in mind, after team-mate Thierry Neuville retired from third on stage eight.
Ogier’s lead secured 18 provisional championship points, with Tanak set to gain 15 points if they both complete Sunday’s four stages.
Hyundai’s Dani Sordo completed the day’s eight stages in third [+2m12.8s, 13 points] ahead of Toyota’s Elfyn Evans [+2m43.3s]. He still claimed a valuable 10 points, after struggling to match his rivals throughout the day.
The pair benefitted from a mechanical issue that put Toyota's Takamoto Katsuta out of the rally.
Sardinia’s attritional stages helped elevate WRC2 class leader Sami Pajari to sixth overall, earning six points, behind M-Sport Ford Rally1 driver Gregoire Munster earning eight points for fifth at the overnight halt.
The leaderboard underwent another shake up when action resumed in the afternoon, as third-placed Katsuta was the next driver to hit trouble after Neuville.
After an oil leak in his GR Yaris’ transmission emerged at the midday tyre fitting zone, the Japanese driver briefly stopped 2.7km into stage nine [Monte Lerno, 25.33km] before pulling off the stage and into retirement.
This handed third to Hyundai’s Sordo while Evans climbed to fourth, 28.5s behind the podium positions.
M-Sport driver Adrien Fourmaux, who rejoined the rally after an alternator issue on Friday, also left the tyre fitting zone six minutes late following repairs to his Puma's brakes. This did change the road order, with Munster opening the road ahead of Evans.
At the front, the rally swung back to Ogier after winning the stage by 6.8s from Tanak, who had been asked by his team “to be safe and not push it,” according to the Estonian. As a result, Tanak’s 3.5s lead quickly turned into a 3.3s deficit.
Ogier claimed stage 10 [Coiluna-Loelle, 14.53km] by 6.4s from Tanak to extend his lead out to 9.7s. Tanak again admitted to taking it easier before stating that he had lost confidence in his i20 N.
“I’m not sure if he is backing off, but I had a better tyre than him for this one, so for sure it is helping,” said Ogier when he was told about the team order affecting 2019 champion Tanak.
“Even if they told him [to be safe], I don’t know why he respects that to be honest. We are having a nice fight, why give up? I don’t think it is him. I cannot judge, it is his situation not mine.”
Evans took 2.9s out of Sordo in the fight for third overall, but the Welshman was still struggling for confidence.
The penultimate stage of the day, a second pass through Monte Lerno, provided a familiar story as Ogier claimed his sixth stage win of the event to push his lead out to 16.2s. This time Tanak, unable to find comfort in the tricky conditions, dropped 6.5s to the Frenchman.
Sordo responded to Evans and increased the gap in the battle for the final podium spot to 32.5s.
Evans rounded off a frustrating day with a fastest time on stage 12 [Coiluna – Loelle]. His effort was 0.4s faster than Ogier, while Tanak was 1.3s adrift.
The rally concludes following Sunday’s four stages.
