Belichick told reporters: "Well, it already happened yesterday. You have to get big contributions from other guys - some at the linebacker position, some at other positions as well - see how it all comes together.
"Keep our fingers crossed for him. See exactly what his situation is, but we have to be ready to move on without him.
"So we will have to put multiple groups, multiple players to do some things that he did. I don't think there's one player that's going to run this team and do all that Jerod did."
Mayo missed 10 games last season with a torn pectoral injury.