The Galatasaray boss believes that his new side showed great determination in their Champions League draw with Juventus and insists that he did not move to Turkey for the money
The Netherlands international joined the Turkish champions from Inter in January in a €7.5 million (£6.3m) deal but has shown only glimpses of his true talent in that time after having been frozen out of the side at San Siro.
Mancini, who was appointed as Fatih Terim's successor on September 30, is determined to see the 29-year-old return to Europe's elite in the coming campaign, along with striker Didier Drogba.
"Players of that level have a certain pride. Sneijder is one of these players. With me, you will see the real Sneijder," he told La Gazzetta dello Sport.
"Didier still has a lot to give but he is working in the right way and offers an important contribution."
Mancini is set to earn more than €12m (£10.2m) in his three-year deal with the Istanbul giants but he is adamant that his move to Turkey was not motivated by money.
"In Italy we always think about money. Everyone says: 'He went to Istanbul for money'. I accepted the proposal because Galatasaray is a prestigious club, participates in the Champions League and has a massive history," said the 48-year-old.
The Super Lig giants secured a valuable 2-2 draw away to Juventus in midweek to restore some hope of reaching the Champions League knockout phase and Mancini is eager to secure points in their next two clashes with Copenhagen to put pressure on Juve and Real Madrid.
"The draw in Turin gives us hope for something more in the Champions League. Juve is always Juve, they are very strong. However, they a Galatasaray who were motivated after a coaching change," said the former Manchester City boss.
"The two clashes with Real Madrid will be pure entertainment. It's an opportunity for us to take advantage of them and get back in contention."