Zenga has Radja Nainggolan on-loan from Inter.
And he revealed, "He's a player available in any situation.
"When I heard Inter wanted Arturo Vidal, I asked why, when they have Radja. That is my thought, but I'm happy to have him here because he makes the difference.
"If Inter leave him for another year at Cagliari, I will be the happiest man in the world."