Bezzecchi grabs pole, Bagnaia on front row for Thai MotoGP
It will be an all Ducati front row for Sunday's 26-lap race at Buriram after Bezzecchi, 23, set a best time of one minute 29.671 seconds, pipping Spaniard Jorge Martin by 0.021 seconds and Bagnaia (0.104 sec).
World champion Fabio Quartararo was fourth-fastest on his Yamaha.
"I didn't know that I was pole position because I couldn't see the big screen in the sun," Bezzecchi said after qualifying in style late in the second session.
"It's unbelievable, big emotions. I'm very proud to make it."
Italy's Bagnaia, who is second in the standings at 18 points behind France's Quartararo with four races left, was in confident mood.
"We did a good job. We had a good pace, we are ready for tomorrow," he said.
In humid but dry conditions, Aleix Espargaro -- who is the third title contender and 25 points behind Quartararo -- finds himself down the grid in 13th for Aprilia.
Spanish six-time MotoGP world champion Marc Marquez on a Honda was eighth.
There are wet conditions forecast for Sunday's race.
MotoGP has returned to Thailand for the first time since 2019 because of coronavirus disruptions.
Meanwhile there were wild celebrations as local hope Somkiat Chantra secured pole position in the MotoGP2 in front of an exuberant home crowd.