Cavani scored the only goal of the game from the spot in PSG's win over Bordeaux on Saturday, but he was unable to finish the match and limped off soon after finding the net, reportedly with a thigh strain.
The form of Paul Pogba and Anthony Martial has hogged all the headlines, and at home, they could well be favourites against PSG when they come visiting for the Champions League clash on Tuesday.
"I don't have good news", said PSG manager Thomas Tuchel.
"I think we have to improve in terms of mentality, attitude and the spirit of sacrifice for the team".
And Tuchel conceded the loss of Cavani, combined with the absence of Neymar, would force him to reevaluate his entire game plan for their biggest match of the season to date - the first leg of their Champions League tie with Manchester United.
This news will come as a huge boost to Manchester United, who have gone 11 games unbeaten under Ole Gunnar Solskjaer, winning 10 of them with one slight hiccup against Burnley, when Victor Lindelof rescued a point.
"There are lots of plan Bs now", Tuchel told reporters.
"If two or three key players are not there, it is our responsibility to find solutions".
There was better news on Marco Verratti, though, with Tuchel confident the Italian midfielder will be fine to play against United despite only completing 60 minutes last time out.
"It is super hard, and if we are missing several players, the challenge is even greater".
"If he comes off, obviously I am anxious".
"A very important game is waiting for us on Tuesday". Verratti played nearly an hour before being substituted by Leandro Paredes.
With Edinson Cavani picking up an injury against Bordeaux, the FC panel examine how PSG would line up if he's ruled out against Manchester United.