Mancini coached one and played for the other, but his allegiances lie with the Blucerchiati...
Mancini coached the Nerazzurri for four years but was sacked in 2008 and will not be supporting them.
His heart will be with 'Doria, where he spent many years as a prolific striker.
The Italian is aware of Inter's strengths, but he is expecting to see the Blucerchiati fight.
"My heart will be with Sampdoria," Mancini told Il Corriere Dello Sport.
"I spent 15 years there. I hope to see a good game because both teams are full of great champions.
"Inter are favourites and they will not be worried by the opposition. However, Luigi Del Neri is a good coach and he will give the Nerazzurri problems."
The spotlight is likely to shine on Antonio Cassano, who has been controversially snubbed by his country. However, Mancini is backing 'Il Talentino' to go to the World Cup.
"Cassano deserves the national team because usually it's the best players who go to the Azzurri, and he has superior qualities to other players," added 'Mancio'.
"He has matured a lot, but the decision is down to [coach Marcello] Lippi."
Salvatore Landolina, Goal.com