The gap could grow as wide as seven points tonight if the Rams beat Reading (18th). Ruben Selles will take his side to Pride Park amidst the latest doom and gloom rumours that the club could be willing to sell its training ground to save funds.
Recent successes for Reading have all come against relegation candidates Carlisle, Port Vale and Charlton.
Bolton will have to bounce back from back-to-back 2-2 draws if they are to take advantage of any Derby slip. They have a tricky home tie in the shape of Oxford, who are just a point outside of the play-offs and will be begging for Posh to do them a favour on Wednesday night.
Oxford ended a four-game winless run on Saturday with a 2-1 victory at home to Cheltenham.
Bolton could only get as far as six ahead with a win but Posh would have two games in hand.
The only place Posh can move is down to fifth if Barnsley can beat bottom side Carlisle at Brunton Park.
It appears on paper to be a good chance to get back on track after a shock 5-1 home mauling against Lincoln against a side who have lost ten of their last 11 games.
Portsmouth also host Burton Albion (20th) and can grow their advantage over Posh to 12 points.
Full fixture list for Tuesday: Carlisle vs Barnsley, Derby vs Reading, Bolton vs Oxford, Portsmouth vs Burton, Fleetwood vs Bristol Rovers, Leyton Orient vs Port Vale, Lincoln vs Cambridge, Northampton vs Blackpool, Shrewsbury vs Exeter, Wycombe vs Wigan.
