The Argentina midfielder, 25, is expected to follow manager Rafa Benitez in a £25m deal should the Anfield club agree.
Mascherano's representative Marco Piccoli said: "There has already been a first contact with director Marco Branca.
"We are evaluating the move hard and in the next few days we will have a new meeting to better establish the details of this transfer deal. There is nothing concrete at the moment, but we are in the talking phase."
Mascherano has also stalled on talks over a new contract at Liverpool.