Zapater played with Milito, now of Inter Milan, at Real Zaragoza and said: "There was interest from several Spanish clubs, but the opportunity to play in the Italian championship and particularly the strong interest from Genoa coupled with the marvellous things I was told by Milito convinced me straight away.
"It's an incredible opportunity for me, they have decided to gamble on me and I want to repay the faith Genoa have shown in me."
Zapater also said he is particularly looking forward to playing with Hernan Crespo, a player he heard a lot about from his Zaragoza team-mate Roberto Ayala.
"Two days ago I left the home I shared with Ayala. He has told me great things about Crespo, because they are close friends. I know the players I will find here, they form a very important team and we have to try and have a good season.
"I'm here to give my contribution in order to help the team achieve as many targets as possible."