Just as Ogier began to edge away due to stage wins on Torsby and Kirkener, Mikkelsen struck back on the Finnskogen stage.
He was quickest of all and reduced Ogier's advantage from 8.6 seconds to just 1.6s.
VW holds all the top three places at present, with Jari-Matti Latvala third.
Mikkelsen leads Rally Sweden
Latvala has been extremely frustrated with his performance in slower sections, but was able to regain time on Ogier on the faster SS4.
He is 6.1s off the lead, and just 2.2s ahead of star returnee Ott Tanak.
The Estonian has managed to keep his M-Sport Ford on the VW pack's tail in his first WRC appearance since dropping out of the series at the end of 2012.
Mikko Hirvonen and Mads Ostberg complete the current top six, ahead of closely-matched Hyundai duo Thierry Neuville and Juho Hanninen.
Last year's Junior champion Pontus Tidemand is ninth on another one-off World Rally Car outing, just ahead of Henning Solberg, who was an amazing second quickest on SS4 on his first WRC appearance in 12 months.
Kris Meeke and Robert Kubica are back in 11th and 12th, driving cautiously to build experience on snow.
Ostberg fastest at Sweden shakedown
Kubica says Sweden was valuable