Jurgen Klopp’s side headed to Serbia for their latest European outing aware of the importance being placed on it.
Liverpool got the job done on home soil when easing to a 4-0 win, but made unwanted history on Tuesday as they slipped to a 2-0 defeat on their travels.
McManaman now fears for last season’s beaten finalists, with the former Reds star telling BT Sport: “They’re struggling away from home and PSG are playing really well at home. So that’s a game that anything could happen if PSG turn up.
“We know Napoli are going to play Red Star at home next, you’d expect them to win that.
“You don’t want to go into the last game needing to beat Napoli or Napoli needing a draw or anything like that. We know how good the Italians are defensively.
“So a real bad performance and a terrible result in the grand scheme of things.
“Losing to Napoli in the way they did and then tonight, not even getting a point just to set themselves a little further forward.
“They’ve really put themselves in a bad position in the group.”
Liverpool are set to travel to Paris to take on PSG on November 28 before bringing the curtain down on their group stage campaign at home to Napoli on December 11.
They have taken only six points from a possible 12 so far, with that return leaving them sweating on a top-two finish and a spot in the last 16.
Their fate is, however, still in their own hands and back-to-back victories from this point would help to rebuild confidence and belief in a continental campaign which is taking place alongside a domestic season that is unbeaten through 11 games so far.