Jorge Lorenzo set the pace in the opening practice session for the Czech Republic MotoGP, beating Marc Marquez whose efforts were not helped by yet another crash.
Fresh from his first back-to-back triumphs of the campaign, Marquez set the early pace on board his #93 Honda.
The reigning World Champ was the first to drop into the 1:56s with 1:56.898 before being joined by Andrea Iannone and Lorenzo. It was tight at the front with the trio separated by a mere 0.095s.
Hammering in the laps, Marquez ran off the track at Turn 13 and although he made a valiant effort to save the bike, skating across the kitty litter, he eventually went down.
While the Spaniard was out of action, Andrea Dovizioso went quickest with a 1:56.821 only to lose the position to Lorenzo as the Yamaha rider crossed the line 0.322s quicker.
Back in the action Marquez recovered to second place while his team-mate Dani Pedrosa made inroads, climbing to fourth and then third.
But as the clock counted down the duo were unable to better Lorenzo's time with the Yamaha rider topping the opening practice session with a 1:56.499.
Marquez was 0.151s off the pace with Pedrosa a further 0.134s down.
Dovizioso dropped to fourth ahead of Iannone and Valentino Rossi. The Championship leader finished the morning 0.539s slower than his team-mate.
Karel Abraham, back on the bike for his home race after missing four rounds due to a toe injury, completed the timesheets in 25th place. He was 5.382s down.
1 Jorge LORENZO Movistar Yamaha MotoGP 1'56.499
2 Marc MARQUEZ Repsol Honda Team 1'56.650 0.151
3 Dani PEDROSA Repsol Honda Team 1'56.784 0.285
4 Andrea DOVIZIOSO Ducati Team 1'56.821 0.322
5 Andrea IANNONE Ducati Team 1'56.914 0.415
6 Valentino ROSSI Movistar Yamaha MotoGP 1'57.038 0.539
7 Bradley SMITH Monster Yamaha Tech 3 1'57.137 0.638
8 Aleix ESPARGARO Team SUZUKI ECSTAR 1'57.597 1.098
9 Maverick VIÑALES Team SUZUKI ECSTAR 1'57.753 1.254
10 Cal CRUTCHLOW CWM LCR Honda 1'57.781 1.282
11 Yonny HERNANDEZ Octo Pramac Racing 1'57.983 1.484
12 Pol ESPARGARO Monster Yamaha Tech 3 1'58.195 1.696
13 Scott REDDING EG 0,0 Marc VDS 1'58.365 1.866
14 Hector BARBERA Avintia Racing 1'58.416 1.917
15 Danilo PETRUCCI Octo Pramac Racing 1'58.445 1.946
16 Nicky HAYDEN Aspar MotoGP Team 1'58.549 2.050
17 Mike DI MEGLIO Avintia Racing 1'58.589 2.090
18 Eugene LAVERTY Aspar MotoGP Team 1'58.656 2.157
19 Alvaro BAUTISTA Aprilia Racing Team Gresini 1'58.669 2.170
20 Loris BAZ Forward Racing 1'58.720 2.221
21 Stefan BRADL Aprilia Racing Team Gresini 1'59.434 2.935
22 Jack MILLER CWM LCR Honda 1'59.559 3.060
23 Claudio CORTI Forward Racing Yamaha 2'00.074 3.575
24 Alex DE ANGELIS E-Motion IodaRacing Team 2'00.122 3.623
25 Karel ABRAHAM AB Motoracing 2'01.881 5.382