Branislav Ivanovic's solitary goal in the 32nd minute not only ruined City's 100 per cent home Premier League record but also ensured the visitors became the first side since Birmingham in November 2010 to keep a clean sheet in the league at the Etihad Stadium.
But despite drawing level on points with their second-placed opponents, just two behind leaders Arsenal, Mourinho continues to stress his team are still some way behind their rivals.
"Two horses and a little horse that still needs milk and to learn how to jump. A horse that next season can race," was the Portuguese's assessment of their chances.
"I don't agree (with their title credentials). We lost points at home against West Brom, against West Ham, we lost at Stoke, we lost at Newcastle.
"We are a team in evolution but this is the kind of performance that helps the team to grow up a lot, tactically, mentally, I think it was fantastic."
Chelsea became the first team to do the double over City since Everton in 2010-11.
"We beat them twice but they are the best team," added Mourinho, who revealed masseur Billy McCulloch gave his team-talk in the dressing room.
"I didn't speak. It was Billy the masseur that spoke to the team. He was screaming so much in Scottish I didn't understand him but the players were clapping. It was Billy's team-talk."
"Today we won because we were the best team. We defended very well, we were very compact, we deserved it.
"A victory is a victory but a victory against a very good team is better than a victory against an ordinary team. More credit to my players.
"We love the big games. Obviously when you love it maybe you feel extra motivated for that and I keep saying, the best thing for the evolution of this team is not to play Europa League, not to be 15-20 points behind the leader but with pressure to be there, to be close to the leaders.
"When we played Arsenal at the Emirates Arsenal were the leaders.
"(This weekend) City were the leaders. This is the best thing that can happen to this team.
"Maybe Arsenal deserve it more than us. They are top of the league and they are the favourites. We go behind them and play and watch."
City boss Manuel Pellegrini played down the significance of the defeat.
"For Chelsea it was a decisive game, not for us," he said.
"If we won we were six points ahead of them. Now we are two points behind Arsenal. We have 39 points to play for.
"Nobody is thinking about records, we are just thinking about winning the games."