Repsol Honda's Casey Stoner was one of four riders to crash within the opening two hours of Thursday's third and final day of MotoGP testing at Sepang.
Officials say the Australian suffered a fast fall at Turn 11/12, but is 'ok'.
However, Honda test rider Kousuke Akiyoshi, who limped away from a heavy crash at Turn 5 just moments later, has been taken to the medical centre for a check-up and may have a wrist injury.
Previous to those falls were spills for Gresini Honda's Hiroshi Aoyama and a test rider.
With almost two hours gone, Aoyama's team-mate Marco Simoncelli leads the timesheets by 0.188sec from Repsol Honda's Andrea Dovizioso, with the Factory Yamahas of Jorge Lorenzo and Ben Spies third and fourth.
Stoner, who led day one, is in fifth place with team-mate and Wednesday pace setter Dani Pedrosa one place behind him in sixth.