Aston Villa have signed four new players this summer.
Di Matteo, who succeeded Remi Garde with Aston Villa this summer, has only signed four players so far.
Tommy Elphick, Pierluigi Gollini, Aaron Tshibola and Ross McCormack - who joined for £12 million from Fulham last week - have all joined Villa so far.
But the Villans' Championship campaign got off to a poor start as Di Matteo's lost 1-0 at Sheffield Wednesday on Sunday to an 86th-minute winner from Fernando Forestieri.
It is hardly the kind of start that the Italian and Aston Villa fans would have been hoping for, but the former Chelsea and Schalke boss says he remains in the market for further reinforcements.
"We are still in the transfer market and looking to add to the squad as well," he told Villa's official website. "It’s difficult to say how different the team will look in a month.
"It depends on the amount of players coming in or going out. I think we have a good core now."
Di Matteo lost Scott Sinclair to Celtic on Sunday. When you consider the 27-year-old's impressive history in the Championship, that will come as a big blow to Aston Villa and Di Matteo will certainly need an able replacement.