Liverpool desperately need United to take points off Manchester City, who will win the title ahead of the Reds if they win all four of their remaining matches.
And Anfield favourite Carragher showed off his ‘new’ outfit ahead of appearing on Sky Sports’ live show for the match.
Posting on his Instagram story on Wednesday morning, the ex-England defender appeared in a Manchester United shirt over his suit and tie.
It was actually as a result of a ‘bet’ with Gary Neville on an episode of Monday Night Football where both wore their rivals’ shirts.
“For one night only!” he captioned the image with.
Sky Sports viewers are no strangers to pundits showing their club allegiances with Carragher’s co-pundit Gary Neville not embarrassed to show off his affection for United.
And fans of the Red Devils will certainly feel torn over Wednesday’s game, with their rivalry with the Reds arguably more fervent than with their city rivals.
Of course, Ole Gunnar Solskjaer desperately needs a win to reinvigorate his team’s hopes of a top-four finish, in particular after their drubbing at the hands of Everton.
That 4-0 defeat should be a positive for Liverpool supporters, according to Neville, who is confident his old club will show a reaction against City and pose a threat to the title favourites.
Pep Guardiola’s side, meanwhile, are on a dominant run of form thanks to ten consecutive Premier League wins.
Beating Manchester United would mean only Burnley, Leicester City and Brighton stand between themselves a a successful defence of their title.
Four victories in their final four games could even lead to the unprecedented scenario of Liverpool finishing second despite collecting 97 points in their 38 games.
The Reds have only lost once all season and yet find themselves cheering on their old foes when the game kicks off at 8pm.
Taking part in the live coverage will be Joe Hart and Roy Keane, creating a curious atmosphere as the Manchester derby kicks off with plenty at stake.