Pompey go in search of a fifth successive victory when they make the long trip to Rochdale this weekend.
Wins over Oldham, Oxford, Walsall and Wigan have pushed the Blues to the brink of the play-off places with just six games remaining.
But they face opponents that are also desperate for points, albeit at the opposite end of the League One table.
Dale have come out on top in their two most recent outings – against Shrewsbury and Bury – to boost their survival hopes.
It leaves them just a single point adrift of safety and with at least one game in hand on the sides around them.
They were left playing catch-up after a memorable run in the FA Cup, reaching the quarter-finals before bowing out to Tottenham in a Wembley replay.
Brett Pitman bagged a brace in a 2-0 Pompey triumph when the sides met on the south coast on the opening day of the season.
But Rochdale were 3-0 victors en route to promotion in the last Spotland meeting – in what proved to be Richie Barker’s final fixture as Blues boss.
Anton Walkes is expected to be fit after missing training on Thursday as a precaution, but Stephen Henderson (groin) and Danny Rose (leg) are injured.
Joe Rafferty could continue in a central midfield role for Rochdale after impressing there in the midweek victory at Bury.
HEAD TO HEAD
Pompey: 5 wins
Rochdale: 1 win
Pompey: 2 wins
Rochdale: 1 win
Seats can be secured at Spotland from the cash turnstiles or at the Rochdale ticket office. Click here for more details.
Overseas subscribers can watch the match live by following the same instructions.
ALSO IN LEAGUE ONE
AFC Wimbledon v Scunthorpe
Blackburn v Southend
Blackpool v Bradford
Bristol Rovers v Charlton
Gillingham v Doncaster
Oxford v Oldham
Plymouth v Peterborough
Rotherham v Fleetwood
Walsall v Bury
Wigan v MK Dons