The Argentine provided the assist as the French midfielder scored the winning goal to hand Roberto Mancini's team three crucial points against Chelsea at the Etihad Stadium.
Nasri and Tevez played a neat one-two resulting in the Frenchman beating Blues' goalkeeper Petr Cech in the final minutes of a cagey encounter at the Etihad Stadium.
"I'm really happy for him [Tevez]," Nasri told Sky Sports. "He's shown great spirit since he came back and he showed today that he can be really important for the end of the season and that's good for the team."
The 24-year-old believes that Manchester City will need to win every one of its remaining Premier League fixtures in order to pip rival Manchester United to the domestic crown.
"It was the same kind of game as in the Europa League against Sporting Lisbon," Nasri explained. "From 1-0 down we showed great spirit and didn't lie down – to win the title, we know we are going to need to win every game."
Defender Micah Richards, who filled in at center back in the absence of Vincent Kompany and Joleon Lescott, was impressed with the character shown by City following Cahill's first goal.
"It's a massive result for us," Richards insisted. "After going 1-0 down, you would have thought our heads would have dropped, but we kept going and managed to get three points and that's the most important thing. It was definitely a test of character, we know Chelsea are a good side. It was a great goal from Samir and we're delighted with the three points.
"We had to win tonight. The manager said that before the game. We came out and gave everything, and showed good character to come back from 1-0 down. We're delighted today."
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