The M-Sport Ford driver set the pace around the 2.55km Velka Chuchle spectator stage that navigated around a racecourse in Prague, as the Czech Republic made its WRC debut.
One of a few crews to opt for four soft tyres, Tanak took the spoils with a perfect run in front of a huge crowd.
Toyota’s Sebastien Ogier, making a seventh WRC start of the season at the penultimate round of the year, was 0.7 seconds slower than Tanak, having opted to run on wet tyres.
Hyundai’s Thierry Neuville produced a committed run through the stage, that featured a mix of asphalt and gravel sections, to clock the third-fastest time, 0.3s slower than Ogier.
Esapekka Lappi posted the fourth-quickest time, some 1.6s in arrears, but the Finn’s rally hopes suffered an early dent.
The Hyundai driver was deemed to have jumped the start, resulting in a 10s penalty, which dropped him outside of the points-paying positions.
Hyundai team-mate Teemu Suninen inherited fourth after Lappi’s penalty, while M-Sport’s Gregoire Munster impressed in only his second WRC start in a Puma Rally1 to sit fifth.
Toyota’s Takamoto Katsuta was sixth-fastest ahead of Toksport Skoda’s Andreas Mikkelsen, who could seal the WRC2 title this weekend.
WRC title rival team-mates Elfyn Evans and reigning champion Kalle Rovanpera set times good enough for eighth and ninth respectively.
Evans edged Rovanpera by 0.1s to take first blood in their private battle. If Rovanpera outscores Evans this weekend he will seal a second world title with a round to spare.
“It was not the best start. We were in the regroup and then the timing changed and we didn’t have much time to get ready for the stage,” said Rovanpera.
“I have a racehorse myself with my friends and I have seen her running on the track but I have never driven on one myself.”
The crews will tackle the 8.92km Klatovy test this evening to complete Thursday’s itinerary, before tackling six more asphalt stages in the Czech Republic tomorrow.
Six stages that straddle the German and Austrian border will make up Saturday’s leg ahead of four stages in Germany on Sunday.
