Valentino Rossi topped a tight third MotoGP Czech Grand Prix practice, in which the top 17 were covered by just a second, while Yamaha teammate Maverick Vinales missed the Q2 cut.
With slightly cooler track temperatures compared to Friday greeting the field at the start of FP3, improvements on FP2 times came in thick and fast.
Marc Marquez, who elected against a time attack at the end of Friday's running, leaped from 10th on the combined standings to top spot with a 1:55.637s, while Honda stablemate Cal Crutchlow moved into second running the hard front and rear combination.
Crutchlow would finally usurp Marquez's times with just under 12 minutes remaining, guiding his soft-shod RC213V to a 1:55.617s to edge just a couple of hundredths clear.
The 2016 Brno race winner's time at the top of the pile lasted only a moment, however, as Pramac's Danilo Petrucci put his GP18 Ducati into first spot with a 1:55.369s.
Jorge Lorenzo, his Ducati fitted with the new aerodynamic fairing Petrucci debuted on Friday, took over from his Ducati stablemate with a 1:55.328s, while Crutchlow crashed at Turn 3.
Petrucci once again took over top spot on his Pramac Desmosedici with a 1:55.261s, while Andrea Dovizioso and Rossi began to light up the timing screens on their final laps as they made their assault on the top 10.
Dovizioso was the first across the line and went 10th, nudging Vinales into Q1 by just 0.058 seconds, while Rossi used the Ducati ahead of him as a reference to leap up to the head of the order with a 1:55.175s.
Petrucci ended the morning second ahead of Lorenzo, while early pacesetter Marc Marquez had to settle for fourth on his Honda.
Friday's fastest man Dani Pedrosa was a tenth adrift in sixth spot, with Andrea Iannone slotting his Suzuki into in between the Honda duo. Crutchlow's crash only cost him a handful of spots in seventh.
Johann Zarco made a late improvement to move into eighth ahead of Tito Rabat, with Dovizioso the last of the runners making direct passage into Q2.
Vinales will face the first part of qualifying along with 12-placed Aleix Espargaro, who headed Jack Miller, Alvaro Bautista and Franco Morbidelli.
Crutchlow's LCR teammate Takaaki Nakagami [23rd] was the only other faller in the session, the Japanese rider – fresh from finishing second for Honda at the Suzuka 8 Hours endurance race last weekend – coming off at Turn 7 10 minutes in.
