After Craig Morgan's summer departure to Preston, Zakuani is Posh's main centre-half but the DR Congo international has a groin injury so Ryan Bennett and new signing Kelvin Langmead will start.
Midfielder Lee Frecklington is out with a knee injury while winger Chris Whelpdale is also absent with a thigh problem.
Posh will be skippered by summer signing Grant McCann while Johnson could also hand debuts to James Wesolowski, Dave Hibbert, Nathaniel Mendez-Laing and Nana Ofori-Twumasi.
George Boyd signed a new contract in the summer to stay at London Road and could prove crucial to the club's ambitions to return to the Championship at the first attempt.
