Ogier raced championship rival Ott Tanak on the Ittiri Arena Show stage, and beat the Toyota driver by a mere 0.3s in what was the final heat.
Lappi was one of the first WRC drivers to tackle the stage after another disappointing rally in Portugal, but made a bright start to lie second overnight, 0.2s up on Tanak.
Tanak’s teammate Kris Meeke was fourth fastest, losing out to Tanak by just 0.1s, meaning only 0.4s separates the leading four crews heading into Friday.
Teemu Suninen made a positive start to his first rally with Mikko Hirvonen’s former co-driver Jarmo Lehtinen. The Finn completed the Ittiri Arena Show stage 1.6s slower than Ogier to sit fifth overall.
Hyundai’s Thierry Neuville and M-Sport’s Elfyn Evans squared off in the penultimate heat, and set an identical time on the short 1.2 mile stage. The pair are equal sixth, 1.8s away from the lead.
Dani Sordo lies eighth overnight, 0.2s behind Neuville and Evans but 0.1s ahead of his Hyundai teammate Andreas Mikkelsen.
Mikkelsen, contesting his first event since his podium on Rally Argentina, beat Toyota’s Jari-Matti Latvala in his heat, with Latvala complaining with brakes “that were not biting” through the water splash. Mikkelsen is 2.1s away from the rally lead with Latvala a further 1.9s back.
after beating WRC returnee Juho Hanninen in his Skoda Fabia R5 by 0.3s in their all-Finnish heat.
with Citroen WRC2 Pro driver Mads Ostberg.