The Argentine striker's career at City looked to be over after he refused to leave the bench to warm up against Bayern Munich in the Champions League last season, and did not play for over five months after being placed on gardening leave by the club.
However, the forward returned to the fold to help City's title push last season, and is now in fine form and fitness.
"Carlos [Tevez] is a top striker, one of the best in the Premier League," Mancini told reporters.
"My relationship with Carlos is good. I am happy with the way we handled [Munich].
"When we started the season this year he was serious and working well for the first time after four or five years," Mancini said.
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Tevez has been in excellent form for the champions this season, and his goal against QPR earlier in September ensured he was the first ever Manchester City player to score 50 goals in the Premier League.Mancini will need Tevez's talents if City are to negotiate a tricky Champions League group, in which they have been drawn against Real Madrid, Borussia Dortmund and Ajax.
"Things haven’t changed. [Tevez] is still a top player and will be important for us.
"[Dortmund] are very good on the counter attack and we expect a very difficult game – it's a really tough group.
"We want to go to the second stage this year so it's important we do well against Dortmund. They are probably our main rivals to qualify. But don't forget they only beat Ajax in the last minute."