The rapid Russian was five seconds faster than Kopecký over the 11.51 kilometres of Semetin, reducing his overall deficit to 1.4 seconds after Kopecký had won the first four stages.
"It's amazing," he said. "It's probably the best stage in the Czech rally, and possibly my favourite stage in Europe. In some places we were cautious because we were driving the stage for the first time but happy with our time."
With Kajetan Kajetanowicz stopping on the road section prior to SS5 and retiring for the day, Lukyanuk has a great opportunity to eat into the Pole's points lead.
Kajetanowicz's demise has opened up a place on the podium, and Tomáš Kostka outpaced Bryan Bouffier in SS5 to grab third place. Pavel Valoušek is fifth and Jan Cerný has leapfrogged Jaromír Tarabus for sixth.
Clickhereto view live results. The next stage is the repeat of Březová, starting 15h03.