The win means that City are back within a point of the Barclays Premier League summit with a superior goal difference of four goals over neighbours Manchester United.
Tevez was named on the bench for Manchester City's Etihad Stadium clash with Chelsea and he was not introduced until the 66th minute, six minutes after Gary Cahill's deflected shot had put the visitors ahead.
Sergio Aguero equalised for City from the spot after 78 minutes after a handball by Michael Essien, and five minutes from time a reverse pass from Tevez found Nasri who guided home the winner.
Thomas Vermaelen's eighth-minute header saw Arsenal past Everton at Goodison Park and was enough for Arsene Wenger's men to jump to third ahead of north London rivals Tottenham.
Vermaelen headed home a Robin van Persie corner for the Gunners, who have now won six in a row in the Premier League in start contrast to Harry Redknapp's side.
Tottenham were fortunate to snap a run of three straight league defeats with a 1-1 draw with Stoke at White Hart Lane, but it was not enough to prevent them falling behind the Gunners.
Cameron Jerome looked set to increase Redknapp's woes when he put Stoke ahead after 75 minutes, but Rafael van der Vaart salvaged a point when he headed home Gareth Bale's cross in injury time.
QPR jumped out of the relegation zone after an incredible comeback at Loftus Road, where they trailed Liverpool 2-0 with 13 minutes to go but ended up winning 3-2.
Sebastian Coates opened the scoring for Liverpool in the 54th minute and when Dirk Kuyt added a second in the 72nd it looked certain to be an eighth game without a win for Mark Hughes' men.
But Shaun Derry pulled one back after 77 minutes sparking a superb finish in which former Reds star Djibril Cisse headed an equaliser four minutes from time and Jamie Mackie swept home in injury-time for a 3-2 win.
Wednesday's Premier League Results
Manchester City 2-1 Chelsea
QPR 3-2 Liverpool
Everton 0-1 Arsenal
Tottenham 1-1 Stoke