With Arsenal's Samir Nasri completing a medical on Tuesday ahead of his £23 million move to the Etihad Stadium, Mancini has already set his sights on the Italy international as he bids to replace the retired Patrick Vieira.
Mancini told Gazzetta Dello Sport magazine 'Extra': “Daniele De Rossi would be absolutely perfect for this team and I rate him as one of the best midfielders in the world.
"I need something else in midfield because we have limited options.
"I have Barry, De Jong, Milner and Toure - but if you consider the number of games in the league, the Champions League and the FA Cup that is not enough.”
Roma would be reluctant to sell but with the midfielder's contract ending in 2012, they risk losing him for nothing in 12 months.
However, Mancini has confessed that De Rossi could spend the rest of his career at Roma.
He added: "But I also have the suspicion that he will stay in Rome his entire career, just like Francesco Totti has done."