The eight-time world champion ended the quartet of asphalt afternoon stages with 4.8s advantage over Rovanpera, as the pair shared the stage win spoils with two apiece.
Ogier had briefly led the rally after Stage 3 on Friday morning, only to lose the lead to Hyundai's Thierry Neuville on the next test, before reclaiming the advantage on Stage 5, which marked the fourth lead change of the rally.
Neuville headed back to the Salou service park 12.5s adrift, while teammate Tanak once again battled a lack of hybrid that saw him ship time in fourth, some 20.0s in arrears.
Home hero Dani Sordo was one of three drivers including Elfyn Evans and Takamoto Katsuta to suffer front left punctures. Sordo did however end the day in fifth, 50.9s behind, but ahead of Evans (1m01.2s), M-Sport's Craig Breen (1m03.7s) and Katsuta (1m28.6s).
All 12 Rally1 entries completed the day's eight stages, covering 118.92 kilometres.
The second pass of the morning stages began under cloudy skies but on a dry yet dirty road surface, negating any significant advantage that could be gleaned from road position.
Ogier claimed his second stage win of the event after the Frenchman pipped Tanak, who had to change an alternator belt prior to midday service.
Sordo and Evans set identical times to sit third fastest on the stage ahead of Rovanpera.
"The feeling is very good in the car and it's even more enjoyable now with higher grip, "said Ogier.
However, crucially for Ogier, the Frenchman was 3.7s faster than the morning's rally leader Neuville, who admitted his pace notes were too cautious.
"I had much more dirt in my notes than there actually was," said Neuville. "I couldn't go faster if I was trusting the notes."
M-Sport enjoyed a much stranger start to the afternoon as Breen was fifth quickest only 3.5s adrift, while 6.8s covered the top 11 Rally1 competitors.
"We're heading in a better direction but I struggled a lot with the car through there," said Breen. "There are some changes I'd like to do but we're in the ballpark now anyway."
Pierre-Louis Loubet recovered from an exhaust issue that forced him to stop on a road section after the morning's final stage, to clock the eighth fastest time.
Light rain arrived shortly after the start of Stage 6, which created a tricky mix of dry and wet sections of road.
Rovanpera faced the best of the conditions which resulted in the Finn claiming his third stage win of the rally, moving ahead of Neuville to second overall. Rally leader Ogier emerged as Rovanpera's nearest rival, albeit 2.2s adrift.
Crews that started the test lower down on the road order were able to make tyre changes to battle the conditions.
As a result, Sordo set the third fastest time ahead of Katsuta, Loubet, Breen, while Tanak, who was second on the road could only manage the seventh fastest time, 0.4s faster than teammate Neuville.
Rovanpera's charge continued into the penultimate stage of the day as he wrapped up another stage win to close in on leader Ogier. The Finn, feeling much more conformable in his GR Yaris, managed to take 0.7s out of Ogier, while Neuville and Tanak let slip more time.
The stage provided plenty of drama for their rivals as Evans, Katsuta and Sordo all suffered front left punctures in the final five-kilometre section.
While Evans and Katsuta were perplexed by their tyre failures, Sordo believed stones that had emerged in a cut were the culprit for his puncture.
Despite the problem, Sordo actually climbed to fifth spot that was held by Evans, who dropped to sixth after losing 56.6s in the stage. The tyre issues helped Breen climb to seventh ahead of Katsuta, who also suffered a loss of hybrid in the test.
Ogier put an end to Rovanpera's fightback by winning Stage 8 by 1.2s from the new world champion, who was lucky to avoid a big moment when he ran wide towards the end of the pass.
Loubet impressed to set the third fastest time, 0.7s faster than Neuville, while Tanak lost the use of hybrid unit again, as 8.1s separated the top 11 on the stage.
Rally Spain continues on Saturday with crews set to tackle another seven stages, comprising 118.75 kilometres.
