If Navas is injured, I could see PSG losing to Leipzig. Navas made some key saves against Atalanta to keep PSG in the game.
Good goalkeeping makes a lot of difference over one game (even over two games).
Oblak performance took Liverpool out of the CL. He didn't make miracles (he is not at fault for the two goals) against Leipzig and they are out.
Ederson didn't have a good game against Lyon and they have lost to a weaker side that has scored on almost all their occasions.
Navas is exceptionally good and Rico is just an average keeper. It might make an huge difference at the end.
It is as damaging as having to play Gabriel Jesus instead of Aguero.