Roberto Mancini's men trailed to a Gary Cahill strike on Wednesday before Sergio Aguero's penalty and Nasri's cool 85th-minute finish gave them the three points.
City have endured criticism of late after a recent defeat to newly promoted Swansea saw them fall a point behind rivals Manchester United in the title race.
However, the 24-year-old believes that his side have recovered from that blow and are treating every game like a Champions League final now.
"After Swansea we could not say anything,” Nasri
|NASRI NOTCHES LATE
|FROM OUR LIVE COMMENTARY|
|86'||That could be a huge, huge goal. Nasri approaches the penalty area and plays the ball into the feet of Carlos Tevez. The Argentine picks out the Frenchman's run with a quick pass and he chips his shot over Petr Cech.|
"We had a really bad game, they played really well, and we were a little bit tired after the trip from Lisbon.
"But after that we recovered and we talked, and said a few things, that we came here to win titles.
"We said that we need to be focused because the 10 games that are left are 10 Champions League finals and we want to win them.
"Since then we have shown great character against Sporting and now against Chelsea.
"There will always be someone there to criticise. Not everyone can like City - there will be some who will say we were weak on Wednesday night.
"But inside the club we believe that we can achieve something together, and that is most important."
Nasri can be backed at 10.00 with 188Bet to be the last goalscorer once again when Manchester City take on Stoke on Saturday.
The Frenchman has been accused of failing to live up to his £24 million price-tag since a summer move from Arsenal.
However, following his impressive display against Chelsea, Nasri insisted that he thrives in pressure situations.
|"Not everyone can like City, but inside the club we believe that we can achieve something together"
- Samir Nasri
"I am not nervous. I play football to play in this type of game - (and have) since I was a kid," he added.
"I love football, and on Wednesday, when you see the atmosphere, the crowd, and the football both teams played - everyone wants to play in this kind of game.
"You have to do something special in this kind of game. Sometimes a player can have pressure, and when a team is winning they try to defend. Then it needs something to open the game.
"Carlos [Tevez] did it with his assist when I scored, and Sergio [Aguero] did it with the penalty.
"You need that in this type of game, otherwise you will not win it - the goals will not fall from the sky."
City face Stoke on Saturday and with United not playing Fulham until Monday, they can regain top spot with victory at the Britannia Stadium.