The Toyota driver started the day with a 10.8s advantage but a stunning drive to sweep the trio of stages allowed the Finn to open up a 52.4s lead over Hyundai’s Dani Sordo.
Sordo's team-mate Esapekka Lappi has moved to third but 57.0s adrift, ahead of the third Hyundai of Thierry Neuville (+57.9s) and M-Sport’s Ott Tanak (+1m34.1s) after Pierre-Louis Loubet crashed his Ford out of fifth on stage 10.
Rovanpera produced the drive of the rally to date on stage nine, the 26.61km Vieira do Minho, after delivering a mesmerising time that was 12.8s faster than Lappi's next best.
Making the most of the starting last of the Rally1 runners, Rovanpera more than doubled his overall rally lead on his way to fifth stage win of the rally.
When asked to explain his speed, he replied: “I just woke up today and thought we should drive a bit of rally, so that is what we tried to do.”
Lappi was unhappy with his performance, but it was enough to climb from fifth to third overall. His effort was 0.5s quicker than Sordo as he began to chip away at the gap between his more experienced team-mate sitting second overall.
Neuville moved his Hyundai up to fourth after M-Sport’s Loubet suffered damage to his rear wing and dropped 6.6s to the Belgian.
The battle at the front changed complexion again on stage 10 after Rovanpera won the 37.24km pass through Amarante, the longest of the rally. The Finn was 3.3s faster than Tanak, who was continuing his recovery from a puncture on Friday’s stage four but struggling with his Puma.
“We could improve the balance a bit from the previous stage, but I am still having quite a massive struggle with the suspension," he said.
Source: Autosport