The championship leader survived slippery conditions to win the three asphalt stages to climb from sitting fourth overnight into a 29.2s lead over Toyota team-mate and title rival Elfyn Evans by 29.2s.
Evans needs to outscore Rovanpera at this weekend’s inaugural three country rally to take the title fight to a deciding round in Japan next month.
Overnight leader Thierry Neuville struggled on the wet roads which demoted the Hyundai driver to third (+30.1s).
M-Sport’s Ott Tanak ended the loop in fourth (+43.8s) ahead of Toyota’s Takamoto Katsuta (+1m17.5s) Teemu Suninen (1m23.4s). The Rally1 field was completed by M-Sport’s Gregoire Munster (+1m31.1s), Pierre-Louis Loubet (+1m31.7s) and Toyota’s Sebastien Ogier (+1m44.4s), who lost time to a puncture. Hyundai’s Esapekka Lappi’s crashed out of third on stage five.
Heavy rain created extremely slippery conditions for crews that favoured those at the top of the road order. Road conditions worsened after each pass as more and more mud was dragged onto the surface from cuts.
Rovanpera, who was first into stage three (Vlachovo Brezi 1 13.66km), made the most of his position, while again showcasing his class, to win the stage by 1.8s from Hyundai’s Esapekka Lappi.
Evans was third fastest, 3.4s adrift, which moved him from eighth to third in the overall standings. Rally leader Neuville struggled with visibility which contributed to him dropping 4.5s in the stage.
“I was struggling to see the road. I opened all the windows I could to get some air in, but it's getting very, very dirty” said Neuville, who led the rally by 1.4s from Rovanpera after stage three.
“Bit of an appeal as well to the spectators because they removed some anti-cuts and suddenly the road was really muddy, so they should keep them in place because for us it was really dangerous.”
Tanak also found the going tough as the Rally Chile winner completed the stage 9.6s shy of Rovanpera’s benchmark. The Estonian was battling with the set up of his Ford Puma and dropped to third overall. The sister Pumas of Munster and Loubet competed the top six.
Ogier encountered the first real issue of the day when his GR Yaris suffered damage to his right front which cost him 41.9s, dropping the Frenchman to 10th overall.
"Unbelievable, unbelievable. What can I say? I can't wait that Michelin is back..,”said an angry Ogier.
WRC2 title contender Gus Greensmith and Adrien Fourmaux also suffered tyre issues, while class leader Yohan Rossel crashed into trees seven kilometres into the stage, ending his title hopes. Rossel and co-driver Arnaud Dunand were okay, but the stage was halted to conduct precautionary medical checks.
The road surface was much wetter in stage four (Zvotoky 23.81km) but it failed to halt Rovanpera. The championship leader produced a stunning effort to take another stage win by a whopping 10.1s from Lappi.
"It was not so easy to get on the pace here,” said Rovanpera. “We got the info that this was to be even more wet than the first one, so I think I was a bit too careful in many places."
Rovanpera’s effort was enough to claim the rally lead from Neuville, who continued to struggle. Neuville endured a couple of wild moments and lost time when he overshot a junction, costing him 19.5s.
"The conditions are really, really tricky. The visibility's bad and we lost the car a little bit in the fast section. I can tell you at that speed with all the surprises, it's really dangerous,” said Neuville, who all 18.1s behind Rovanpera.
Evans adopted a careful approach to complete the stage with the third fastest time, 14.6s behind Rovanpera.
After his turn issue in the previous stage, Ogier admitted he’s lost his motivation as he dropped a further 41.4s.
Rovanpera completed a clean sweep of the morning stages after winning stage five (Sumavske Hostice 1 23.43km) by 6.4s from Evans, who climbed to second overall ahead of Neuville, who dropped 12.0s.
The headlines however belonged to Lappi who fired off the road, 1.2km into the stage. The Finn and co-driver Janne Ferm were okay but their i20N suffered heavy damage to the rear putting it out of action for the afternoon.
Fourmaux claimed the lead in WRC2 after championship lead Andreas Mikkelsen lost more than 10 minutes following an off in stage four.
Crews will repeat the trio of Czech Republic stages this afternoon.
