Torres took full advantage of City goalkeeper Joe Hart's latest defensive calamity to net the winner in a 2-1 victory for the Blues against one of their main title contenders.
"This is a goal of belief," Torres told chelseafc.com.
"I used to have a team-mate who told me every ball can be the most important ball of the game, and this is a clear example, a long ball and a misunderstanding and you have the ball to pass into the net. I was lucky.
"I am feeling good and with high confidence, and feeling better in the system we are playing with more space.
"Hopefully we can keep improving as a team as it is just the beginning of the season and important games are coming."
Following two goals in last week's Champions League win at Schalke and a first Premier League goal of the season, there is talk of a return to former glories for Torres, who has been much-maligned since his £50million move from Liverpool.
Yet it took a woeful first-half miss to rouse the World Cup-winning Spain striker before he set-up Andre Schurrle's opening goal and netted the winner following Sergio Aguero's equaliser.
After draws at Manchester United and Tottenham, it was Chelsea's first significant scalp in the Premier League this season.
"We are happy because it is our first win against one of the contenders for the Premier League title," Torres added.
Next for the Blues is Tuesday night's Capital One Cup fourth-round clash at Premier League leaders Arsenal, who are two points ahead of Mourinho's men in the standings.
The scheduling of the fixture, coming with just a day's rest after the City match, means Jose Mourinho will make wholesale changes.
Torres is likely to drop out, so too is Schurrle, depriving the German of an on-field reunion with some of his compatriots in Mesut Ozil and Per Mertesacker.
"It's no surprise for me that Mesut is playing so well," Schurrle said.
"I'll be happy to see him and Mertesacker because we have a good team spirit in the national team and we are all good friends, but tomorrow, for 90 minutes, there are no friends.
"The manager will change many positions but we have high quality in every member of the squad and there will be no problem for us.
"I think Arsenal will change their players, too, and it's going to be a good match.
"I am very happy to be a part of our squad, and with a team like Chelsea you want to win every competition you are in, so we'll do everything tomorrow to win the match."
Mourinho twice won the League Cup in his first spell at Stamford Bridge and twice won the Premier League.
Chelsea have won the championship once since, in 2009/10, and finished 25 points adrift in sixth in 2012, when they won the Champions League, and 14 off the pace in third last term, when the Europa League was won.
Branislav Ivanovic believes that, after extending the 100 percent start at home with a fifth win, the current squad are as good as the one which lifted the Premier League under Carlo Ancelotti.
The Serbia defender said: "We have a different team now to the one that won the league in 2010, but maybe we have the same quality and performances (as that team) to win the league this season.
"We have a strong enough squad, if we stay at this level to be competitive.
"To be champions and stay at the top all season, it is very important to get maximum points from every game.
"Sometimes it may be only a point but we have to get something from every game, especially when we are at home. We're doing that well this season.
"The champions aren't decided now, but it was so important for us to beat Manchester City because these kind of games give you confidence and extra points when you are fighting for them.
"I hope it's going to help our confidence and in the next games as well."