The teenage Finn ended Friday’s first full day with a 19.6sec lead over Skoda Fabia team-mate Jan Kopecký after a tough leg of asphalt speed tests in the Mosel vineyards and Saarland lanes.
After taking the lead in Thursday night’s short curtain-raiser, Rovanperä won four of the six speed tests to distance his Czech colleague, leaving Kopecký facing an uphill battle to repeat 2018’s result when he defeated Rovanperä.
“I think we can’t do more. If I push more then some small mistakes would come. I can’t go any faster,” said Kopecký.
Mads Østberg was almost a minute off the lead in third, the Norwegian unhappy with the brakes and gearbox of his Citroën C3. Eric Camilli was a further 20.8sec adrift in his Ford Fiesta.
Stéphane Lefebvre produced a remarkable drive on his first appearance in WRC 2 this season to lead by 8.1sec from fellow Frenchman Nicolas Ciamin.
Lefebvre has not competed at world level since last October and has started only two national rallies in his home country this year. He powered his Volkswagen Polo into the lead this morning and was never headed, winning two tests.
Ciamin, also in a Polo, reeled off four fastest times in a row this afternoon but could only claw back a handful of seconds.
Former German champion Fabian Kreim was 24.0sec adrift in third in a Fabia, but almost 20sec clear of fellow countryman Marijan Griebel. Fabio Andolfi and Kajetan Kajetanowicz fought hard for fifth, Andolfi edging the Pole by 3.6sec.
Nikolay Gryazin’s hopes of moving into the championship lead took a severe knock when the Russian dropped two minutes with a puncture and he languishes in 12th.
Simone Tempestini was a place behind after dropping almost 3min 30sec in the opening test with a similar problem in his Hyundai i20.