Blues boss Alex McLeish has revamped his squad this summer and hopes to complete the signing of Sporting Gijon midfielder Michel after the weekend.
But he has decided that McSheffrey, signed from Coventry three years ago, and the much travelled Bent are surplus to his requirements,
McLeish said: "Are there any players going out? We've spoken to a couple of players and told them and their agents that we will listen to offers for them.
"It may happen before the window closes. We anticipate one or two might leave.
"I have spoken to Gary McSheffrey and Marcus Bent and said that, unfortunately, when you bring new players in, you have to make some sacrifices.
"We will listen to offers for these lads. Hopefully the agents are working around the clock to help their clients.''
McSheffrey made a big impact in his first season and scored 15 goals before Christmas during the 2006-2007 campaign.
But since then he has shown only glimpses of his best form.
As regards signing Michel, McLeish said: "The window closes soon, and when it closes, we won't be able to do more business. That is why we need to try and strengthen the squad.
"With Michel it is an ongoing dialogue and nothing will happen before the weekend. I am hoping we can have a couple of new players next week.''