Liverpool is hoping for a favour from its rival, with Jurgen Klopp's men two points clear atop the Premier League but with Manchester City holding a game in hand.
United goes into the derby at Old Trafford on the back of six losses in its past eight games, including a 4-0 thrashing at Everton.
Fowler, appointed coach of A-League club Brisbane Roar said it was hard to see United turning its form around.
"I think obviously everyone knows my allegiances are massively with Liverpool and I think if we're being totally honest it's going to be tough for them because you feel as though Manchester City can beat anyone on their day," Fowler said. "They've got four games to play and obviously they're four winnable games.
"So, to use a little bit of mind management if you like, I think Manchester United need to pull off a big favour for Liverpool.
"I think the way they're playing at the minute, you can't see it happening, but stranger things have happened."
United is chasing a Champions League qualification place, Ole Gunnar Solskjaer's men three points adrift of fourth-placed Chelsea ahead of the derby.