McManaman believes Liverpool have a chance of coming away from Old Trafford with a positive result.
The Reds have taken seven points from their opening four games and after initial positive signs in the opening three matches, they go into the crunch clash looking to bounce back from a humiliating 3-0 defeat to West Ham United before the international break.
McManaman said in the Liverpool Echo: “We should learn a lot more about this Liverpool side on Saturday.
“A lot of the top teams haven’t started particularly well. I think some of that inconsistency is down to trying to integrate a lot of new players.
“If Liverpool can win at Old Trafford people will change their opinions about what the club can achieve this season.”
The former midfielder said the Reds will not be facing the Manchester United of old this weekend as they are still going through a transitional phase themselves, and have started the season in a similar manner to Liverpool by picking up seven points to start the season and have struggled for goals.
He added: “It’s still very early in the season but Saturday feels like a really important game for both clubs.
“Playing the way they do, I think it might suit Liverpool playing away from home. They will be able to hit United on the counter-attack."
The Reds will be without Philippe Coutinho at Old Trafford through suspension which is admittedly a blow, but could be seen as an opportunity for the side as there is the element of surprise they could use against Louis van Gaal's side, as the Brazilian has been at the centre of a lot of the Reds' play so far this season.
It will be an interesting game for both sides as they look to bounce back from defeats before the international break. Usually, one would expect this game to be a tight affair as a result but both sides will be desperate to land an early-season blow on the other.