Johann Zarco topped a MotoGP session for the first time since taking pole at Le Mans, after edging Andrea Dovizioso by 0.073s in Czech Grand Prix FP1.
Championship leader Marc Marquez began the second half of the 2018 campaign by leaping to the top of the timesheets early on in FP1, setting the pace with a 1:57.884s.
The Honda rider – who tested at Brno following the Dutch TT – proceeded to lower his best time to a 1:57.297s, which he improved on his third flying lap to a 1:56.828s.
Marquez remained unchallenged at the top of the standings for the next 10 minutes, before Ducati's Dovizioso transformed his 0.2s deficit to a 0.1s lead over the Spaniard when he fired in a 1:56.720s.
Dovizioso's lap came under some threat as the session neared its conclusion, and it was finally beaten by a last-gasp effort from Tech3's Zarco, who put in a 1:56.647s on final lap to secure top spot.
Dovizioso remained in second, 0.073s down on Zarco, with Marquez completing the top three with his early effort of 1:56.828s.
Alvaro Bautista hovered around the top three for the entire session, and was fourth after Zarco's lap at the end of FP1 aboard his Aspar Ducati, while Valentino Rossi rounded out the top five on the first of the factory Yamahas.
Andrea Iannone ran second fastest briefly in the closing stages, but the Suzuki rider was shuffled back to sixth when the dust settled.
Dani Pedrosa headed Honda stablemate and wildcard Stefan Bradl in seventh, while Jack Miller edged ahead of fellow GP17-runner Tito Rabat in ninth.
Jorge Lorenzo endured a low-key session on his factory Ducati down in 12th, a tenth down on LCR Honda's Cal Crutchlow. Maverick Vinales was a similarly quiet 14th on the second of the factory M1s.
Franco Morbidelli returned to action this morning after withdrawing from the German Grand Prix with injury, and was 22nd with a 1:58.299s.
Suzuki wildcard Sylvain Guintoli, making his first MotoGP appearance since the Catalunya round, was 19th aboard an updated GSX-RR, sandwiched between KTM's Pol Espargaro and the second Marc VDS Honda of Tom Luthi.
