Pajari, who is just 21 years old, had set the pace in the premier support category for much of Friday’s opening leg but fell behind Huttunen as a result of a front left puncture.
He trailed his fellow Škoda Fabia RS Rally2 driver by 12.9sec heading into this penultimate day but clawed back an amazing 10.0sec in the wet-weather opener at Västila.
Huttunen, caught napping, then doubled his buffer with a strong response on the legendary roads of Päijäla but later pulled over in the second pass of Vekkula. A technical issue meant he went no further and promoted Pajari back to the fore.
The youngster, who holds an impressive seventh in the overall rally standings, leads M-Sport Ford Fiesta Rally2 driver Adrien Fourmaux by 33.9sec going into Sunday’s four-stage finale. Victory in Finland would be the first at this level for Pajari and co-driver Enni Mälkönen.