Superpole winner Jonathan Rea (Kawasaki Racing Team) secured his first race win of the 2018 season in front-running style after resisting early attacks from team-mate Tom Sykes, who faded to finish sixth at the end, and seven seconds down after 20 laps of heat and humidity.
With clear track ahead of him Rea pushed on and managed the gap behind, winning by just over 1.5 seconds.
The remarkable Leon Camier (Red Bull Honda World Superbike Team) was first to relegate Sykes down the order and he looked on for a podium finish, until he was chased down and passed by first Xavi Fores (Barni Racing Team Ducati) and then Chaz Davies (Aruba.it Racing – Ducati), who ended up second and third respectively.
With the top three spots filled, Camier was fourth and the advancing Alex Lowes (Pata Yamaha Official WorldSBK) fifth, jumping Sykes near the end to finish up top Yamaha rider.
Michael van der Mark (Pata Yamaha Official WorldSBK) came home just behind the Lowes/Sykes battle, in seventh.
Marco Melandri (Aruba.it Racing – Ducati) experienced a huge wobble at one stage of the race and dropped a place immediately, finishing up only eighth.
Eugene Laverty (Milwaukee Aprilia) was a second behind Melandri, with Jordi Torres (MV Agusta Reparto Corse) right with him across the line.
The top ten riders were separated by just 11 seconds.
On his first visit to Chang Loris Baz (GULF ALTHEA BMW Racing Team) placed 11th. American riders PJ Jacobsen (TripleM Honda World Superbike Team) and Jake Gagne (Red Bull Honda World Superbike Team) were 17th and 18th respectively.
In the championship Rea is now only two points behind Melandri, 58 to 56, with Fores third on 49 points. Race two takes place at Buriram on Sunday.