Following the question marks over the Arrows team, who were unable to take part in the latter part of last season due to financial difficulties, Mosley has also suggested that other teams may struggle to make the grid in 2003.
"It would be nice to have 22 cars but I think 20 is more probable," he said.
"Not necessarily because of Arrows, but because there are another team or two that are not 100% in good shape.
"But we are keeping our fingers crossed that they will be there in March."
The official line-up for the new Formula One season will be announced by the FIA in early December. However, the 11 teams that competed last season are all said to have paid the £200,000 entry fee for the 2003 championship by last Friday's deadline.
Other than the Arrows outfit, other teams known to be struggling financially include Minardi and Jordan.
Max Mosley, head of motorsports governing body the FIA, has warned that Formula One could lose two teams before the new season starts.
