In the corresponding fixture in October, the Blues thrashed Mourinho's men 4-0 at Stamford Bridge.
Chelsea were also 1-0 winners when the two sides met in the FA Cup last month.
During that game, Mourinho was involved in a bust-up with Chelsea fans and after the match claimed “Judas is still No1”.
And given the bad blood between the teams, Merson is predicting a draw and points dropped for the Premier League leaders.
Manchester United boss Jose Mourinho
He told Sky Sports: "A big game. I can see Chelsea dropping points considering what happened to Jose Mourinho at Stamford Bridge earlier this season.
"Some fans had a bit of a go and he will make it difficult for his old club.
Jose Mourinho gestures at Chelsea fans
"It should be a good battle between N'Golo Kante and Paul Pogba in midfield. They are very different players, though, and I don't think it's fair to compare the two.
"Pogba will be a success. At the moment he's a young kid carrying a big price tag. You judge him next season and if he has a shocker then it's different."
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