The Blues can shop for players in January after the suspension of FIFA’s transfer ban pending appeal.
Terry believes the club need to go into the market in case they lose thier fight against FIFA’s two-window punishment.
He said: “It’s good news about the transfer ban being suspended but we lose four good players to the African Nations Cup in January anyway.
“I’m sure the club and the manager are looking into that and having good talks with Roman.
“I wouldn’t be surprised if we do go out and buy because we don’t know what’s going to happen in the summer – or the following summer.”
He added: “We’re going well at the minute and we’re lucky enough to have a big squad with good players who can come in if we get a couple of injuries.
“Looking at it realistically, we’re maybe going to be suspended in the summer window and maybe another one after that.
“The manager has great experience and he knows what we need.”