Lampard is entering the final year of his contract and revealed this week the club had yet to follow up last term's initial talks about a new deal.
The 34-year-old insisted he would "love" to stay on but there now appears to be a real prospect he could leave next summer.
Blues boss Di Matteo was coy about revealing whether he had recommended to the Chelsea board that Lampard was offered an extension but asked whether he was hopeful there would be a successful conclusion to any talks, he said: "I am, yes."
He added: "These are talks between the club and the player.
"I've been very happy with Frank and he shows his qualities that he has in every game that he plays, so a very influential player within the group as well."