The Portugese believes it would make the Stamford Bridge outfit almost certainties for Champions League qualification this season.
Should Chelsea beat their own opponents West Ham at Stamford Bridge and City win at White Hart Lane, Mourinho's third-placed squad will be 10 points clear of Spurs, who are challenging Liverpool, Everton and Manchester United in the battle to compete in Europe's elite competition next term.
Chelsea have narrowly clung on to their Champions League status in recent seasons, finishing sixth in the Premier League in 2012 and gaining a reprieve by winning the European Cup before a year later being certain of their qualification only after a final-day victory over Everton.
Even though Chelsea's next opponents are City, on February 3, Mourinho would like Manuel Pellegrini's team to prevail at Spurs.
"I prefer them to win, because if they win and if we win, we open a gap to Tottenham," Mourinho said.
"If we have a gap of 10 to Tottenham, 12 to United, you have a safe spot in the Champions League.
"If you can have a safe spot by February and play the rest of the season without that pressure, it would be fantastic for us."
Champions League qualification is Mourinho's primary target on his return to Stamford Bridge after again playing down his side's title prospects.
"That's an objective I don't want to fail," he added.
"We cannot fail, because as a club we need that and as a team we need that too, because we want to play Champions League.
"As a team it's very important for the evolution of the team, as a club it's very important for financial reasons, for prestigious reasons.
"The top four, if possible the top three, is the big, big, big objective and it's a difficult objective.
"If everybody is there, you go to the end of the season under big pressure, so for us it will be better for City to win."
Put to him that he was beginning to sound like Arsenal boss Arsene Wenger, who has spoken of the importance of Champions League qualification amid his side's near nine-year run without a trophy, Mourinho's response was curt.
He added: "It's not a trophy. It's a moment of the evolution of this team. Next season I will be speaking differently."
Mourinho and Wenger have had a to-and-fro argument over fixtures of late, with the Portuguese insisting Arsenal always have the better deal.
It is something Mourinho believes was enforced when the March fixture schedule showed Chelsea playing Arsenal on Saturday, March 22 at the end of a fallow midweek for the Gunners, while the Blues will have met Galatasaray in the Champions League.
Nevertheless, Mourinho, who favoured a Sunday match with the Gunners, welcomed the prospect of a contract extension for Wenger at the Emirates Stadium.
Mourinho, who has spoken of his desire to emulate Wenger's longevity, added: "It's fantastic to give that stability, that example. Maybe others follow, because I think it's a good thing. I am happy for him."
Mourinho believes long-term success for Chelsea is dependent on players such as Eden Hazard, who recently spoke of his desire to be one of the world's best players alongside Real Madrid's Cristiano Ronaldo and Lionel Messi of Barcelona.
"If he wants to be a great, great player and arrive where Cristiano and Messi arrive, he has space to go because he's 23," Mourinho said.
"It's a great ambition for him. What I feel now with him is responsibility in every aspect.
"Against Man United I saw him make a fantastic tackle inside of our box, but at the same time against Stoke he was trying to kill the game, not waiting for things to happen but trying to make things happen.
"The kid is going in a fantastic direction."
The Ballon d'Or is the trophy FIFA award to the world's best player, but it is one Mourinho does not value, even if Hazard covets it.
Mourinho said: "Without an entourage and politics, he doesn't get the gold ball."
Last summer Mourinho tried to team Hazard up with Wayne Rooney at Chelsea and had two bids for the England man rejected by Manchester United, with whom the striker appears close to signing a new deal.
Asked about Rooney, Mourinho said: "I feel nothing. I don't care. I'm happy for him if he gets a fantastic deal."