Chelsea will head to the Etihad Stadium three points adrift of City, who replaced Arsenal at the summit after crushing Tottenham Hotspur 5-1 at White Hart Lane on Wednesday.
A victory against Manuel Pellegrini's side will see Chelsea draw level on points with them, but Mourinho believes his team are not yet ready to be installed as genuine title contenders.
"We are not favourites to win any competition," he said, before vowing that Chelsea will pose a greater threat next term.
"The speech will change completely next pre-season, and not just the speech
Normally the speech is adapted to the feelings, knowledge and experience.
"Next pre-season, day one, I will say we are candidates to win the Premier League
This season, I won't say that
It's not what we feel or what we're working for.
"If we win or if we lose (at City), I don't think we're candidates
If we win, obviously, we're the same points as City
If we lose, the distance is six.
"It doesn't matter
It is not what concerns me
What concerns me is my team playing well and trying to get the best possible results, feel the improvements.
"And next pre-season, you will hear me say something completely different
I don't give up
I'll try to win the next match, against whoever
We will try to win."
Mourinho's efforts to build for the future have been strengthened by the signing of Kurt Zouma, the France Under-21 defender, from Saint-Etienne for a reported fee of around £12 million ($19.8 million, 14.6 million euros).
The 19-year-old centre-back has signed a five-and-a-half-year contract, but will remain on loan at his current club for the remainder of this season.
"He's another young player in the profile of some Chelsea signings in the last few years
We like the profile
We think he's very much adapted to the Premier League," Mourinho said.
"If you don't do it now, probably we couldn't do it in the summer because other clubs were also very strong on him
So we did it
Now he stays at Saint-Etienne.
"Pre-season he'll join us
We'll see if it's to stay or go on loan, but he's a young player in a position where we also need the future."
Zouma follows Nemanja Matic, Mohamed Salah and Bertrand Traore into the club this month, prompting Mourinho to hail the long-term foundations being laid down at Stamford Bridge.
"The greater objective is the improvement of the team and preparing the team for the future," he said.
"To do something now as an emergency plan is not the best thing
The players we're signing now are the right ones for our future: Matic, Salah, Zouma, a young kid for the future.
"We don't sign a striker now as an emergency plan to score half a dozen goals to give us half a dozen extra points, whatever they mean for us
So we're waiting for the summer to do the right thing in that area."
Source : AFP