Despite several of the FIA World Rally Championship's leading crews running into trouble on the gruelling gravel stages in the mountains around León, Lappi steered clear of drama to head Ogier at the first gravel round of the season.
The Hyundai i20 N star led from the outset after grabbing the top spot in the morning’s opener. But Ogier, who ironically alternated drives with Lappi at Toyota Gazoo Racing last season, stayed right on his heels, with the duo exchanging times for much of the day.
It was, however, Lappi's impressive performance in the latter half of the afternoon which made all the difference. Back-to-back stage wins in Las Minas and Las Dunas gave the Finn some much-needed breathing space and, while Ogier clawed back some time in the Distrito Leon super special, 5.3sec split the pair at close of play.
"I am a bit surprised, but I take it as it is,” Lappi beamed. “This was probably one of the best days of my career.
“I always hoped that I could fight at the top, but to be leading and fighting against Séb was never in my mind. I didn't really think about how this day would go, but I was just confident that our pace would be good."
Elfyn Evans filled the final podium spot, finishing 24.8sec behind his Toyota GR Yaris team-mate Ogier. With temperatures nearing 30°C and altitudes of over 2750 metres, it was a trying day for crews and cars alike, but the Welshman’s struggles were limited to a lack of traction on some of the stages.
Thierry Neuville was hampered by hybrid unit failure in the morning, followed by a seized rear-right damper and damaged driveshaft boot in the afternoon. He pressed on regardless, reaching the overnight halt 9.7sec adrift of the podium in his Hyundai.
Starting second on the road, defending champion Kalle Rovanperä was severely affected by the loose conditions. As a result, the Yaris driver lost time in almost every test, ending the day a 19.9sec down on Neuville.
Meanwhile, Dani Sordo leaked around a minute when he limped through SS7 with rear-left tyre damage on his Hyundai, dropping from fourth to sixth overall.
Championship leader Ott Tänak languishes more than 14 minutes back from the lead after crawling through the morning loop with turbocharger failure. It was a disastrous day for the Estonian’s M-Sport Ford team as both Pierre-Louis Loubet and Jourdan Serderidis retired their Pumas in the opening stage.
Also in trouble was birthday boy Takamoto Katsuta, who lost control of his Yaris in a high-speed section on SS5 and rolled down a steep embankment.
WRC2 leader Gus Greensmith was seventh ahead of support category challengers Adrien Fourmaux and Emil Lindholm, while Kajetan Kajetanowicz completed the top 10.
Saturday’s leg is the longest of the event and features nine more challenging stages totalling 126.52km.