The Finn - celebrating his 22nd birthday today - started on the back foot when he was dealt a five-second penalty by rally stewards for breaching hybrid strategy rules.
Friday pacesetter Ott Tänak and his Hyundai team-mate Thierry Neuville were both handed identical punishments, gifting the top spot to Elfyn Evans before any cars had even turned a wheel.
Rovanperä’s despair was short-lived, however, and he cut through the pack with a clinical drive on tricky terrain as the land of the long white cloud continued to live up to its name with more relentless rain.
Jumping onto the podium after leapfrogging Yaris colleague Sébastien Ogier in Kaipara Hills, the 22-year-old found himself leading the field with a blistering time on the very next test while Evans spun and Tänak fought with car set-up.
Gus Greensmith’s spectacular roll on the final Komokoriki test caused the stage to be cancelled - allowing Rovanperä's lead to stand at 4.6sec over Tänak before the loop is repeated this afternoon.
“Gus went off on a very fast place but the main thing is that they are okay,” Rovanperä said after completing the stage non-competitively.
“For me, I was hoping to have a good road position for today and so far I have been able to push, so it’s good.”
WATCH: Evans spins, picks up extensive damage
Rovanperä’s current standing means he would simply need to outpace Tänak on Sunday’s bonus points-paying Wolf Power Stage to seal the drivers’ title. With Tänak unhappy in his Hyundai, any further position drops would make Rovanperä’s job even more straightforward.
“I have no feeling in the car,” said the frustrated i20 N driver. “We can’t do anything and we have no speed. It’s nothing new.”
Ogier made a poor start but pulled 5.3sec from Tänak through the tricky and technical Puhoi stage. The Frenchman is poised to pounce this afternoon and filled the final podium spot just 1.9sec behind his rival.
WATCH: Big impact roll ends Greensmith's day
Evans was relieved to only be 36.2sec in arrears after the cancellation of SS10. His Yaris clouted a banking during the spin, suffering heavy damage to the front and rear which resulted in him and co-driver Scott Martin refilling the car’s radiator using drinking water.
Almost half a minute back was Neuville, who struggled through the morning after losing third gear on his i20. Team-mate Oliver Solberg moved into the top-six following Greensmith’s demise, ending the loop 6.8sec clear of Toyota youngster Takamoto Katsuta.
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