The race, scheduled to start at 11pm local time, was delayed just as the riders were about to start the formation lap, and got cancelled half an hour later, when the rain intensified.
The riders were concerned that, as well as the track being covered in standing water, visibility would be almost non-existent as the light from the floodlights reflected off the water and spray.
A midnight meeting between the teams and the organisers resulted in the decision to postpone the race to a 9pm local time slot on Monday, following a new warm-up at 6:30pm.
The 125cc event had already been truncated after only four laps, with riders being awarded half points, while the 250cc round was also forced to be shortened to 13 laps to allow the MotoGP race to start on time.
The decision to postpone until Monday evening received a mixed response from riders.
Pole-sitter Casey Stoner is concerned that the weather could intervene again, although current forecasts suggest better conditions tomorrow night.
"This is not a good idea," Stoner told Gazzetta dello Sport. "We have no guarantee it won't rain. Today's downpour has also brought sand over the track, so there's also a safety risk."
But Hayate Kawasaki rider Marco Melandri felt that having travelled to Qatar and gone through practice and qualifying it made more sense to race on Monday than to reschedule for later in the season, amid suggestions that Losail should take the September slot left vacant by the Hungarian GP's cancellation.
"For sure I would like to race tomorrow and go on holiday in September," Melandri told the official MotoGP website.
"We are here, we've been testing for days, and we are ready. It's going to be hard to change all the plans but I don't want to go back home - I want to race, because I've had a smell of the race and then had to come back into the garage."
