For Monday's visit of Tottenham, Smalling will operate at right-back, with £16.5million capture in 19-year-old Jones and 23-year-old Jonny Evans serving as centre-backs.
"Losing Vida is disappointing. He's been such an influence over the years, and especially last season," said Smalling on Vidic, who is out for up to five weeks with a calf injury.
"A lot of our stability was down to him, so it's important other players now step up to the mark, but he's going to be a big loss for whatever period he will be out.
"However, with the amount of games we have there are going to be people who pick up injuries, or people who lose form, so there are going to be a lot of opportunities.
"It's down to you to step in and make the manager decide not to take you out of the team."