Rovanpera managed to tame changeable conditions to win three of the four high-speed gravel stages to lead Toyota team-mate Elfyn Evans by 3.9s at midday service.
Hyundai’s Thierry Neuville completed the loop in third (+12.3s) while Toyota’s Takamoto Katsuta inherited fourth (+16.0s) after Esapekka Lappi crashed out in stage five.
Teemu Suninen (Hyundai) and WRC returnee Jari-Matti Latvala completed a reduced Rally1 field after M-Sport duo Ott Tanak and Pierre-Louis Loubet exited the rally in stage three. Oliver Solberg headed into Friday afternoon in seventh as the fastest of the WRC2 runners.
Overnight rain created damp road conditions which played into the hands of Rovanpera, faced with the task of opening the roads as the points leader.
The Finn managed to usurp overnight rally leader Tanak by setting the third fastest stage time on stage two, as Toyota dominated the timing screens.
"Quite slippy conditions, the grip is not so good, so definitely not so easy,” said Rovanpera, who was 1.3s adrift of the ultimate pace. Team-mate Katsuta took the stage win, making the most of his road position to pip Evans.
Lappi was the quickest of the closely-matched Hyundai trio as 0.6s covered the 2017 Finland winner, Neuville and Suninen. After winning Thursday’s opening stage, Tanak was a tenth slower than Suninen although the Estonian wasn’t entirely comfortable.
Moments later disaster struck Tanak and the M-Sport team as its pair of Ford Pumas retired from the day’s action on stage three. The 2019 world champion suffered a loss of power at the six kilometre mark during the famous high-speed Lankamaa test, which has returned to the rally in this format for the first time since 1993.
An impact to the bottom of the car triggered the issue that resulted in Tanak grinding to a halt with grey smoke coming from the bonnet. He was briefly able to to engage EV power before pulling off on an exit road. He retired after extinguishing a fire.
To rub salt into the wounds, the sister Puma driven by Loubet clipped a rock to cause terminal damage to the left-rear suspension.
Amid the drama, Rovanpera clinched his first stage win of the event, pipping Evans by 1.8s to move into a 2.2s overall rally lead. Neuville emerged as best of the rest by clocking the third fastest time ahead of team-mate Lappi, who was struggling to unlock more speed from his Hyundai.
Meanwhile, Toyota team boss Latvala’s tentative start to his first WRC outing since 2020 continued as the three-time Finland winner elected for a controlled approach. “I know I could go faster, but I need to take risks and I am not quite at that level,” he said.
Meanwhile Toyota maintained its strong start to the rally on stage four (Myhinpaa, 15.51km) where Rovanpera again edged Evans by 1.4s to post a second fastest time of the day.
Lappi was third fastest, 2.6s adrift, although the Finn was faster than Hyundai team-mates Suninen and Neuville.
“I am doing everything I can, I am very disappointed for myself," said Lappi. "I cannot drive any faster, no chance."
However, Lappi’s hopes of repeating his 2017 success were ended by a nasty crash during the following stage five (Halttula, 9.14km).
The heavens opened ahead of the stage, creating a slippery road surface. Lappi drifted wide at a high-speed right hander and suffered a heavy impact with the trees lining the road, causing significant damage to his I20 N. Lappi and co-driver Janne Ferm were unhurt in the impact.
The stage was won by Rovanpera, who encountered the worst of the rain shower. The reigning world champion was 0.3s quicker than Evans, as the pair continued their intense fight at the front.
The field will repeat the morning stages this afternoon followed by a run through the Harju super special this evening.
