Cheered on by thousands of enthusiastic fans in dry but increasingly cool conditions, Kopecky took 7m06.7s to complete the 9.36-kilometre course in his ŠKODA Fabia Super 2000.
“This is nothing, tomorrow it’s a different story,” said the European championship leader.
“Today in the city was full of spectators and thanks a lot to everyone who came but tomorrow the rally starts again.”
Vacláv Pech was second fastest in his MINI John Cooper Works S2000, 3.2s down on Kopecký with Tomáš Kostka third in his Ford Fieta R5.
Pavel Valoušek was fourth quickest in another Fiesta R5 with Sepp Wiegand and Roman Kresta rounding out the top six respectively.