Rovanpera leads Portugal Rally after see-saw day
There were five different stage winners but it was Rovanpera who held the initiative, the Finn following a fifth place in the day's opening stage with top-three times in the remaining seven tests.
Eight-time champion Ogier, however, produced a stunning show in the Mortagua finale to put the pressure on Rovanpera when the action starts again on Saturday.
"It has been a great battle the whole day," said Rovanpera, the two-time defending WRC champion.
"I could not do much more (in the last stage) because my tyres were in such bad condition at the rear and it was just about surviving.
"(The battle) is only fun if you are winning, so let's see!"
Japan's Takamoto Katsuta, who won the first stage of the day, finished 4.7 seconds off the pace in third overnight.
Spanish driver Dani Sordo won three stages but that was only good enough to leave him in fifth, behind the Estonian Ott Tanak.
Thierry Neuville won the fourth stage of the day but otherwise had a poor day at the wheel and now finds himself down in sixth place, 18.1sec behind the leader.
Britain's Elfyn Evans had an even worse day as co-driver Scott Martin misplaced his pace note book, containing crucial details of every twist and turn of the stage.
Martin quickly set up his mobile phone to access a digital copy of the notes.
But the British pair had further problems when their Toyota GR Yaris sustained front-right tyre damage during the stage, costing almost one minute.
They will start Saturday in eighth place 1min 43sec behind Rovanpera.