Marquez 'okay', will try to ride

Marc Marquez will try to continue the Thai MotoGP weekend, where he has a chance to wrap-up an eighth world championship, after a massive morning highside required a trip to hospital.

Marquez - who needs to score two points more than Ducati's Andrea Dovizioso to secure his fifth MotoGP crown on Sunday - dominated opening practice before being dramatically caught-out in the closing stages, after joining the track on new soft tyres.

The Repsol Honda rider was launched into a vicious highside when the rear lost grip on entry to Turn 7, which is the first real right-hander when joining the circuit from pitlane.

The rear of the Spaniard's RCV was destroyed as the bike cartwheeled down the track, with Marquez clearly in pain at the side of the track.

A stretcher was prepared to help him away but the #93 eventually got to his feet and limped slowly to a waiting ambulance, which took him to the medical centre.

Marquez, strapped to a stretcher, was then moved back to the waiting ambulance, which took him to a local hospital for further checks on his left leg and back.

"Marc had a big crash as you all saw. Fortunately, he's okay. He went to the medical centre and then hospital to check everything. They did an MRI and everything looks fine," said team manager Alberto Puig, speaking in the Buriram paddock at lunchtime.

"Of course, he has some contusions in the back and the leg but nothing to be worried about. He was lucky, fortunately.

"He will have some treatment, go out [in FP2] and try to continue the plan."

Marquez is now back in the paddock and walking unaided.

Some paddock gossip suggested Marquez's carbon fibre swingarm might have failed, rather than being broken after the highside, but Puig said a dirty tyre was the most likely cause.

A picture of the incident later posted by Marquez also seemed to show the swingarm undamaged before the bike began bouncing down the track. 

"Well the thing was that… on the back straight probably he was not on the correct line, I mean he was on the outside line and looks like that area is a little bit dirty," Puig explained.

"The tyre got some dust there and it's one possibility that the tyre was not completely clean. That was probably the reason because he was not going fast and the tyre was up to temperature, so probably it was a matter of some dust or dirt on the tyre."

Maverick Vinales and Fabio Quartararo went on to lead a Yamaha one-two in opening practice, with Marquez in third and Dovizioso fourth.

Buriram is the first of five chances for Marquez to lift the crown, holding a 98-point lead with a maximum of 125 points up for grabs.