Jari-Matti Latvala extended his Rally Finland lead to 19.7 seconds by the end of Friday, as Kris Meeke grabbed second from Sebastien Ogier.
Reigning World Rally champion Ogier felt running first on the road was much more costly for him amid the afternoon's fully dry conditions.
Latvala countered that being second in the start order was little different for him, and felt his Volkswagen team-mate and title rival had outpsyched himself.
As well as falling away from the flying Latvala, Ogier was also reeled in and overhauled by Meeke's Citroen, which grabbed second halfway through the afternoon loop.
Meeke will go into Saturday with a 1.6s advantage over Ogier after his best drive of the year so far.
Kubica and Ogier quiz each other
Fourth place remains very hotly contested. Mikko Hirvonen began to escape from the battling Mads Ostberg and Andreas Mikkelsen, only to fall back again with a spin on the Paijala stage.
The trio were briefly covered by just 0.8s before spreading out on the closing Harju stage. Mikkelsen is now 1.2s ahead of Ostberg, with Hirvonen another 1.9s apart.
Hyundai had to retire Thierry Neuville's car during the lunchtime service when rollcage damage was discovered from his morning incident.
But the team was able to revive Juho Hanninen's i20 - which did actually roll in his earlier crash, unlike Neuville's - and the Finn was immediately back on the pace after service.
Power steering issues then set in, slowing his recovery, and Hanninen ended the day ninth, edging closer to Elfyn Evans.
That means rookie Hayden Paddon is now established as Hyundai's lead runner in seventh.
A string of punctures for Henning Solberg and a crash for Martin Prokop mean Craig Breen now completes the potential points-scorers in 10th.
M-Sport has successfully repaired Robert Kubica's Ford following his crash at the start of Friday's action.
He will rejoin under Rally2 on Saturday, albeit far down the order with heavy penalties.
Follow Rally Finland as it happens on AUTOSPORT Race Centre Live from 8.45am UK time on Saturday morning
Leading positions after SS13:
Pos Driver Team/Car Time/Gap
1. Jari-Matti Latvala VW 1h34m42.4s
2. Kris Meeke Citroen +19.7s
3. Sebastien Ogier VW +21.3s
4. Andreas Mikkelsen VW +1m04.2s
5. Mads Ostberg Citroen +1m05.4s
6. Mikko Hirvonen M-Sport Ford +1m07.3s
7. Hayden Paddon Hyundai +2m11.6s
8. Elfyn Evans M-Sport Ford +2m39.4s
9. Juho Hanninen Hyundai +2m51.1s
10. Craig Breen Kel-Tech Ford +5m19.1s