Danny Mills thinks the title race will "almost" be over if Manchester City beat Manchester United on Super Sunday.
Pep Guardiola's side lead their city rivals by eight points ahead of the derby match at Old Trafford and if they win their 14th straight league match, they will move 11 points clear after just 16 matches of the season.
Former City defender Mills says the result of the game is tough to call, but that if the visitors leave with all three points then it will make them virtually "uncatchable" both in terms of points and mentality.
"Manchester City are one of the best teams in Europe, if not the world, to watch at the moment," Mills told Sky Sports News.
"They are incredibly exciting, while Mourinho is a bit more pragmatic.
"Mourinho, of course, always has this knack in a one-off game of being able to get a result and it's going to be very, very interesting to see.
"If City were to win this, are they uncatchable? It's going to be very, very difficult to catch them because of the confidence it will give them.
"The lead it will give them will be not quite, but almost, unassailable."
Mills were speaking at an event for the first anniversary of the EFL Trust Disability programme which aims to help disabled people get into sport.