That’s the verdict of former Arsenal star Martin Keown, who says the Portuguese may be forced to alter his approach.
United are currently second in the table having collected 23 points from their opening 11 games of the Premier League season.
They’re a distant eight adrift of Pep Guardiola’s leaders City, who have a favourable run of fixtures after the international break.
United welcome City to Old Trafford on Sunday December 10 in a game which might have a huge bearing on the Premier League title race.
Keown has suggested Mourinho could abandon his usual counter-attack tactics in the hope of securing three points when he goes up against old foe Guardiola.
“I have been in situations where you feel invincible and everyone is saying nice things about your team,” Keown told the Daily Mail.
“But Pep Guardiola’s Manchester City team haven’t won anything yet. They don’t know what’s going to happen for the rest of the season.
“If we want the Premier League to be more competitive, we have to hope that someone can take points off them.
“They have been helped by the fact that their rivals have been chipping away at each other. United beat Tottenham and then lost at Chelsea. Those results are perfect for City.
“We have a Manchester derby on the horizon at Old Trafford at the start of December. By then, Jose Mourinho may feel he has to go for it. A draw will not be good enough.
“It has the potential to be a rip-roaring game… and it will be fascinating to see if Mourinho changes his tactics to win this big game.”
United will be looking to get back to winning ways when they play host to Rafa Benitez’s Newcastle on Saturday November 18.