Marc Marquez returned to the track for FP2 at the Thailand Grand Prix on Friday having been hospitalised following a crash in FP1.
The Spaniard, who will seal a sixth MotoGP world title if he gains two points more than championship rival Andrea Dovizioso at the Chang International Circuit, lost control of the rear of his Repsol Honda in the closing stages of his out-lap in the opening session.
Marquez launched into a highside and hit the ground heavily, with his bike totally wrecked from multiple rolls, and the rider visited a local hospital for checks on his leg and back following an initial examination at the circuit.
However, shortly before FP2 began, Marquez tweeted to say he was okay.
"Hard crash this morning but fortunately we are fine," he wrote next to a picture of him coming off his bike.
Honda team boss Alberto Puig admitted Marquez was "lucky" to escape serious injury.
"He had a big crash, as you all saw, but fortunately he's okay," he told reporters.
"We went to the hospital to check everything, they did an MRI and everything looks fine.
"Of course, he had some contusions in the back and also in the leg, and also here in the hip a little bit, but nothing to be worried about. We were lucky today.
"He will have some treatment probably, and he will go out and we will try to continue with our plan."
Marquez then set the fastest lap of the day early on in FP2.