The Posh boss believes Micky Mellon will transform the club into promotion contenders in the month ahead.
So that means the League One club will not be taking their foot off the gas ahead of the first round match on Saturday.
Mellon wants to use the FA Cup to help the club’s Vanarama National League improvement - and not hinder it.
And McCann knows up-and-down Peterborough can’t afford to take Tranmere’s challenge lightly.
“They have a squad full of experienced players with plenty of Football League matches between them,” McCann said.
“They will be well organised by a good manager and they have two strikers who have goals in them.
“Tranmere have suffered a slow start in the National League, but they have started to hit form and I expect them to be promotion candidates again this season.”
He told Peterborough Today: ““My strongest possible team will play against Tranmere. I want us to play well and entertain obviously, but FA Cup ties are all about winning and getting through to the next round."