Grealisk is offered for sale this summer by City and this month was omitted outside their World Cup team.
After leaving City to Napoli last week, De Zon says that De Bruyne has spoken about the qualities of Grealiskh about Napoli Chiefs.
City is willing to sell Grealisk for £ 40 million, but much will depend on his willingness to accept payment equipment to make a move to Naples.
Currently at £ 300,000 a week in City, Grealishe can expect little more than half as a Napoli player.