Chelsea captain John Terry believes Liverpool could struggle to put their Premier League title challenge back on track because Rafa Benitez's squad doesn't have strength in depth.
While Liverpool have suffered badly whenever Fernando Torres and Steven Gerrard are injured, Chelsea shrugged off Didier Drogba's three-match European ban by starting their Champions League campaign with a 100 percent record.
Nicolas Anelka and Salomon Kalou have both scored important goals for Chelsea in Europe this season, but in stark contrast, Liverpool - without Torres - slumped to a 2-1 defeat at home against Lyon on Tuesday.
That loss was Liverpool's fourth in a row and another defeat in Sunday's match against Manchester United would all but end their rivals' title hopes.
Asked if Benitez's men will be out of the title race if they lose to United, Terry replied: "When Stevie and Torres get injured they seem to be very short in the squad they've got.
"We're very fortunate at Chelsea. Since Roman Abramovich came we have had a lot of strength in depth in the squad, like with Salomon Kalou scoring twice against Atletico with Didier Drogba being out.
"People said we would struggle without Didier, but we didn't. If you take Torres out of their team, who do they bring in? It's difficult.
"We have players that are not here only to make up the numbers, but players that are fighting and working hard every day in training to come in and really prove themselves.
"Salomon seems to always come in and do well. Didier knows that the players behind him are working hard and wanting his place, the same goes for Nico. When Salomon comes in and does well, it gives the manager a real problem."
Despite Terry's fears for Liverpool, Anfield boss Benitez is refusing to panic ahead of the United match.
"The main thing going into these games is that you stay calm," he said.
"You cannot afford to think too much about if you win or lose before you've even played the game. That doesn't help.
"It is very important when you play against the top sides to show character and belief.
"That is what we must do on Sunday against United. It's really important to stay calm and think about one game at a time. That has always been the message and always has to be.
"This season, the top sides will lose more games, I'm sure of that. We will see more teams losing points against teams that they have perhaps been used to winning against."