The 33-year-old joined Manchester United on a free transfer on deadline day, and was expected to make his debut against Newcastle after the international break.
But it has emerged that he may have to quarantine for two weeks before he can be involved for his new club and as a result he may miss the meeting with Newcastle.
The rules for elite athletes are different if they are entering the UK from a secure bubble they were already in, but Cavani was in Paris and was mixing with the general public.
For the moment, Manchester United are unclear on the protocol and have contacted the UK government to seek clarification over Cavani.
Manchester United want him in training with the rest of the squad as soon as possible, but at the moment it seems he will not be seen at Carrington for a while.
Not having Cavani would be a blow for Ole Gunnar Solskjaer, who will be missing Anthony Martial from his squad against Newcastle due to suspension.
Cavani could be in line to make his debut against his former club Paris Saint-Germain in the Champions League.
