Brno - Spain's Honda rider Marc Marquez, five-time world champion and current championship leader, will start the Czech Moto Grand Prix in Brno on pole after heading Saturday's qualifying.
It was a sixth pole of the season for Marquez, who finished 2.524 ahead of Australian Jack Miller (Ducati), with KTM rider Johann Zarco in third for Sunday's race.
In difficult weather conditions at the end of the second session Marquez was the first to dare to change tyres to deal with the rain.
"I took all the risks, even if my team wasn't happy about it," he told French broadcaster Canal+.
Frenchman Zarco, 17th in the overall standings, claimed his first top 10 start of the season.
"It's an ultra difficult period and this type of result lifts my spirits," he said.
"I don't know if it means if I can win but it shows I can feel I still have the ability to do so," he added.
Marquez has notched up five victories from the nine races of this 19-race season and sits 58 points clear of Italian Andrea Dovizioso, who won in Brno last season.
The 26-year-old has chalked up two wins at the Czech circuit, in 2013 and 2017, and last year finished third behind the Ducati's Dovizioso and Jorge Lorenzo, who has since become his teammate at Honda.
The grand prix is due to start at 14:00 SA time with the weather forecasters warning further rain and storms during the race.
Leading grid positions for Sunday's Czech Grand Prix after qualifying at Brno on Saturday:
1. Marc Marquez (ESP/Honda), 2. Jack Miller (AUS/Ducati), 3. Johann Zarco (FRA/KTM)
4. Andrea Dovizioso (ITA/Ducati), 5. Pol Espargaro (ESP/KTM), 6. Alex Rins (ESP/Suzuki)
7. Valentino Rossi (ITA/Yamaha), 8. Danilo Petrucci (ITA/Ducati), 9. Maverick Vinales (ESP/Yamaha)
10. Fabio Quartararo (FRA/Yamaha-SRT), 11. Cal Crutchlow (GBR/Honda), 12. Franco Morbidelli (ITA/Yamaha)
1. Alex Marquez (ESP/Kalex), 2. Sam Lowes (GBR/Kalex), 3. Lorenzo Baldassarri (ITA/Kalex)
4. Nicolo Bulega (ITA/Kalex), 5. Fabio Di Giannantonio (ITA/Speed Up), 6. Marco Bezzecchi (ITA/KTM)
7. Marcel Schrotter (GER/Kalex), 8. Bo Bendsneyder (NED/NTS), 9. Jake Dixon (GBR/KTM)
1. Tony Arbolino (ITA/Honda), 2. John McPhee (GBR/Honda), 3. Niccolo Antonelli (ITA/Honda)
4. Tatsuki Suzuki (JPN/Honda), 5. Raul Fernandez (ESP/KTM), 6. Aron Canet (ESP/KTM)
7. Makar Yurchenko (KAZ/KTM), 8. Jaume Masia (ESP/KTM), 9. Ai Ogura (JPN/Honda)