MotoGP riders will get additional Qatar Grand Prix tracktime on Saturday, to evaluate wet track conditions.
Heavy rain hit the Losail circuit overnight, with more falling throughout the day, while storms are forecast for Saturday evening.
Riders are not convinced running under lights in the wet will be safe, despite a trial by officials conducted earlier this year.
That has raised the possibility the 2017 season opener could be rescheduled, to either earlier on Sunday - during the day - or even delayed to Monday night as was the case in '09 if the conditions are not suitable for racing.
Work to dry the circuit has been carried out during the day, but several large patches of water remain on the front straight ahead of a safety inspection.
The three practice sessions completed so far have been in the dry, but organisers have scheduled an additional 20-minute session for 6pm local time on Saturday, for MotoGP competitors to assess the track.
Some riders have also expressed concerns that the wet circuit would lack grip, and that evaluation session will be followed by a Safety Commission meeting at 6:30pm, where the balance of the schedule will be discussed.
The times for fourth practice, from 7:55pm local time, and qualifying, 8:35pm, are currently unchanged.