The 28-year-old has failed to consistently reproduce his best form at Stamford Bridge since moving from Anfield in January last year, with former Blues boss Roberto Di Matteo dropping him for the 3-0 Champions League defeat to Juventus.
But despite his lack of goals, Mancini believes the striker is "always dangerous", and after linking up with former Reds boss Rafael Benitez, thinks the striker's "difficult moment" could be over.
"Two years ago we had a chance of signing Torres but after the price became too high we decided on other players," he told reporters.
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Torres scored 81 in 142 appearances at Anfield, but has only hit 19 in 87 games since making his big-money move to the Champions League winners.
Mancini spoke of the failed move ahead of the City's clash with Chelsea on Sunday afternoon, and insists his players should be right to fear the Spaniard's talents if they are to take the points away from Stamford Bridge.
"He's a good player. Every striker can have a difficult moment but for me he is always dangerous," he added.