Valentino Rossi could be forced to miss the entire second day of MotoGP testing at Sepang in Malaysia due to sickness.

Ducati has confirmed that the Italian, who had been ninth fastest on Tuesday, was taken ill overnight and has received treatment in the Clinica Mobile this (Wednesday) morning.

Testing runs from 10am to 6pm and Rossi is the only rider not yet out on track. It looks increasingly likely that Rossi will soon return to his hotel.

The seven time MotoGP world champion had been planning to making detailed refinements to his Desmosedici today, having chosen a base set-up for both his bikes after day one.

Rossi is the second rider to face sickness this week, rookie Cal Crutchlow having suffered food poisoning on the flight over to Malaysia.

Wednesday marks day five of the eight days of 2011 pre-season testing available before the start of the racing season.