The Reds' loss to The Saints in the first leg of the semi-final was just Jurgen Klopp's side third defeat all season in all competitions and comes at a pivotal stage in the campaign.
Southampton's Nathan Redmond celebrates scoring their first goal
The return of Philippe Coutinho is a huge fillip for Liverpool. The Brazilian's appearance from a near two month absence just after the hour mark at St. Mary's signalled a greater attacking intent from Klopp's side.
With the Merseysiders without a win since New Year's Eve versus Manchester City, Sunday's visitors will be keen to make a statement to league leaders Chelsea.
Since the beginning of December, Jose Mourinho Manchester United has greatly improved winning all of their last nine outings across the board.
Manchester United's Marcus Rashford celebrates scoring their third goal
The Red Devils have not conceded a goal in 270 minutes - dispatching Reading with the minimum of fuss last weekend in the FA Cup Third Round.
Despite this, United have not played any of the top five team in the English top-flight during that period. Sunday is set be the first real test of their newly-inherited credentials.
This weekend's clash will be the 35th times the two have met since the turn of the Millennium. Over the last ten meetings, United edge the contest 5-3.
Liverpool manager Juergen Klopp and Manchester United manager Jose Mourinho at the end of the match
When Klopp and Mourinho met for the first time in the Premier League back in January, a typically stalwart United showing stifled Liverpool, as the spoils were shared in a turgid goalless draw. Is a similar fare on the cards again?
Jose Mourinho has doubts over two individuals ahead of Sunday. Zlatan Ibrahimovic is struggling to shake off an illness, whilst Marcos Rojo could miss out with a muscle injury.
Here is how Manchester United could line up:
For Liverpool, Philippe Coutinho could make his first start in seven weeks, with both Jordan Henderson and Joel Matip being assessed late on to face United. Marko Grujic is absent again, whilst forward Danny Ings is a long-term absentee.
Here is how Liverpool could lineup: