Marcel Schrotter topped Friday's Moto2 running ahead of the Czech Grand Prix, the German setting the pace in both practice sessions.
Schrotter opened up Friday's running fastest of all in FP1 with a 2:03.854s ahead of Romano Fenati.
Schrotter set the early pace aboard his Intact GP machine with a 2:04.850, which he improved to a 2:04.086s having been briefly usurped by Fenati.
A final improvement of 2:03.854s followed for the German with half the session gone, and this remained intact as the chequered flag brought FP1 to a close 25 minutes later.
Championship leader Francesco Bagnaia shadowed Fenati in third spot, while Andrea Locatelli and Alex Marquez rounded out the top five.
Mattia Pasini laid the gauntlet with a 2:03.359s at the beginning of FP2, though Schrotter soon returned to top spot with a 2:03.208s, which he bettered on his follow-up tour to a 2:03.118s.
Bagnaia put Schrotter's time under some threat, but could only manage a 2:03.319s, and was unable to advance any further on that in second spot.
Schrotter remained unchallenged for the remaining 35 minutes following his best lap, giving the German a clean sweep of the Friday timesheets at Brno.
Pasini completed the top three behind fellow Italian Bagnaia, while Marquez was just over a tenth further adrift in fourth spot ahead of Fabio Quartararo.
Jorge Navarro's Moto2 future remains uncertain as his difficult 2018 campaign continues. However, the Gresini rider made a promising start to the Brno weekend, guiding his Kalex to sixth spot with a 2:03.508s.
Fenati dropped to seventh in the afternoon session, while Joan Mir, Lorenzo Baldassarri and Simone Corsi completed the top 10.
The hot track temperatures caught a number of riders out across both sessions, but only two crashed. Eric Granado fell at Turn 1 in FP1 early on, while Khairul Idham Pawi crashed at Turn 11
