There are 42 places between Championship side Posh and their opponents from League Two so a home win will be long odds on.
But there were 89 places between Posh and non-league Chorley when the sides met in a second round tie at London Road last season.
And Posh were promptly humbled 2-1 in front of the live TV cameras despite taking a second minute lead through Jack Taylor.
“I only have to think back to last season to make sure we don’t take anything for granted on Saturday,” Posh boss Darren Ferguson said. “Of course we have a great chance to get through because we are playing a League Two side at home.
“But we were hot favourites to beat Chorley and yet we were outplayed and deserved to lose.
“I just want to get through this tie and I don’t care how we do it.
“Reaching the fourth round would be a big financial boost for us and it would do us the world of good confidence-wise.
“Any win in any competition is good for morale and if we can take care of business against Bristol Rovers it would give us a big lift before we take on some very dificult Championship fixtures though. It’s not an easy game anyway. They have good experience in their side particularly in midfield with Paul Coutts and Anthony Evans.”
Posh are likely to field a full strength side given they haven’t played a competitive match since losing 3-1 at Blackpool on December 18.
The only confirmed absentee, alongside long-term injury victims Jack Marriott and Dan Butler, is summer signing Joel Randall who has a slight hamstring issue.
Teenage striker Ricky-Jade Jones could be in the matchday squad for the first time since damaging knee ligaments in a Carabao Cup tie against Plymouth in August. He was denied a run-out for the under 23s against Burnley on Tuesday because of Covid cases in the opposition camp.
Saturday’s tie will be played to a finish on the day. There are no replays in the third and fourth round of the FA Cup this season to ease fixture congestion. Extra time and penalties will be used if needed.