United face a potential banana skin in the EFL Cup against League One side Northampton tonight.
"If Jose Mourinho needs momentum then this game should be perfect for him," Nicholas told Sky Sports.
"You can see there are issues in the team - there are big egos and they are finding it tough to adapt.
"Mourinho will be telling his players he wants to win this trophy because he knows it will take the pressure off him.
"The other teams will make changes and, while we probably won't see Zlatan Ibrahimovic or Wayne Rooney start, Anthony Martial and Marcus Rashford will, while Paul Pogba should get a chance in Rooney's position."