Steve Cotterill's side have seen their lead at the top of the table cut to just a point following 1-0 defeats to Swindon Town and Preston North End, who sit second and third respectively.
City will be without captain Wade Elliott once again after he was sent off in the defeat against Swindon, but face a Peterborough side who have problems of their own.
Darren Ferguson's men have dropped down to seventh spot following a dismal run in which they have picked up only one point from their last five matches in the third tier.
Back-to-back home defeats in the league against struggling Scunthorpe United and in-form Swindon ensured they dropped out of the top six and Ferguson will be expecting a response.
Swindon outlined their promotion credentials by beating the leaders and Peterborough in their last two outings and Fleetwood Town will try and halt their charge on Saturday.
Mark Cooper's side have reeled off three consecutive wins in League One and have lost just once at the County Ground in the league this season, while Fleetwood suffered a 1-0 home defeat to Walsall last weekend.
Fourth-placed MK Dons are five points behind Cotterill's side with two games in hand following a 2-2 draw with Rochdale in midweek and face Colchester United at home this weekend.
Crewe Alexandra dropped to the foot of the table after suffering a 4-1 drubbing at Leyton Orient last time out and will aim to stop the rot against Doncaster Rovers at Gresty Road following four games without a win.
Jordan Clarke's late double ensured Yeovil Town ended a miserable run of eight league matches with a win and four without scoring when they beat 10-man Notts County 2-1 at Meadow Lane to move off the bottom of the table last weekend.
Manager Gary Johnson will be hoping that is the sign of things to come ahead of a home clash with Preston, while Mark Robins' Scunthorpe side travel to his former club Barnsley on the back of a three-game unbeaten run in all competitions.
Sheffield United take on Notts County at Bramall Lane, Rochdale host Oldham Athletic in a Lancashire derby and Chesterfield travel to Crawley Town.
The other games on Saturday see Coventry City entertain Walsall, Bradford City host Leyton Orient and Gillingham at home to Port Vale.