Genoa president Enrico Preziosi has expressed his disappointment after Jose Mourinho pulled the plug on a deal for Mancini at the last minute.
The Brazilian winger was expected to join either Genoa or former club Roma this summer after failing to make an impact under Mourinho at Inter Milan since signing last summer.
However the Inter boss has decided to keep hold of the 29-year-old, whose contract runs until 2012, much to the frustration of Preziosi.
Having lost two of last season's squad to the Nerazzurri already this summer, with Thiago Motta and Diego Milito heading to the San Siro, relations between the two clubs were already strained before the Mancini saga.
"I am sad for Mancini," Preziosi said to Radio Incontro.
"We had spoken to the lad and his wish was to join us but at the last minute, Mourinho has not give the go-ahead.
"I don't understand why, perhaps it's because the Portuguese coach fears us or that he feels the player with us could have rediscovered his form."