Ogier, 39, who is not driving a full season, leads Rovanpera by 16.7 seconds ahead of Sunday's finale.
The race is down to a two-car battle between the Toyotas of Ogier, eight-time world champion, and Rovanpera, 22, the defending champion.
More than two minutes behind in the seventh round of 13 this season are the two other Toyotas with Welsh driver Elfyn Evans and Japan's Takamoto Katsuta.
Since returning to the calendar in 2021, Kenya has the reputation as one of the toughest rallies on the circuit.
Ogier triumphed in 2021 and Rovanpera last year.
Hyundai drivers Thierry Neuville and Ott Tanak, who started the race second and third respectively in the standings, suffered in the Safari.
Belgian Neuville retired during Friday's fifth stage with a broken suspension, with Estonian Tanak, suffering a puncture later.
Neuville was nevertheless able to grab some consolation on Saturday, in particular the bonus points for the Power stage.
Nevertheless, in the general classification, Ogier could catch Neuville, Evans and Tänak and even overtake them despite the Frenchman not competing in all the rallies this season.
Absent in Sweden and Portugal, he will still miss races.
Ogier and his partial programme is therefore not a direct competitor for Rovanpera, and the Finn knows it.
"I think we could push a bit more, but for sure Seb is pushing a lot for this victory. In our case we also have to think about the championship," he said.
Hyundai's disastrous weekend continued with Finn Esapekka Lappi withdrawing with a mechanical problem.
