The Finn looked almost unstoppable on home turf and his Movisport-prepared Volkswagen Polo GTI R5 was well-suited to the superfast winter speed tests.
A spin costing 20sec in the darkness of Siikakämä 2 caused a brief scare, but Lappi was fastest on every other stage and ended the penultimate day with a 49.8sec advantage over Andreas Mikkelsen.
“We have great conditions, fast roads, and big banks. It’s been very good so far - we have a big lead, but we can’t make any mistakes,” he said.
Mikkelsen, driving a Skoda Fabia Rally2 for Toksport, pushed hard to stay on Lappi’s tail. The Norwegian admitted he was already driving on the limit and didn’t have much more to give.
Nikolay Gryazin was 36.0sec behind Mikkelsen in third. He had a scare of his own earlier in the day when he swiped a snowbank with the front end of his Movisport Polo.
Despite dropping almost 40sec, the youngster has a healthy 1min 5.7sec gap to fourth-placed Eyvind Brynildsen in another Toksport Skoda.
Ole Christian Veiby completed the top five in a Hyundai i20 R5. Throttle issues on Friday cost the youngster precious time and he arrived back to Rovaniemi on Saturday evening 2min 53.7sec adrift of the leaders.
Que c'est frustrant ! Un petit fossé, en accélérant à la sortie d'un virage, 1 roue, puis 2, et nous voilà piégés. ????♂️ pic.twitter.com/T29JGgQ6dC— Adrien FOURMAUX (@AdrienFourmaux) February 27, 2021
Czech star Martin Prokop was 3min 10.0sec further back in an M-Sport Ford Fiesta Rally2, followed by Citroën man Sean Johnston, who was another 7min 30.9sec behind after getting stuck in a snowbank on Friday. Georg Linnamäe was 7min 53.8sec down on Johnston in eighth.
Frenchman Adrien Fourmaux was caught out by the second pass of the challenging Mustalampi blast. He went off the road after 20.9km and was unable to extract his Fiesta from the snow. The M-Sport Ford hotshot will restart on Sunday.
- Full coverage from Arctic Rally Finland Powered by CapitalBox is available on WRC+ All Live here, including every stage broadcast as it happens as well as key interviews, features and expert analysis from the service park.