Nine points separate the 11th-placed Blues and the Tykes, who currently occupy sixth place and the last League One play-off place.
Victory would see John Mousinho’s side reduce that deficit to six points.
Anything else and it’s becoming difficult to see Pompey making up that ground, despite 19 games left to play.
Indeed, the Blues would require teams above them to start dropping significant points as we quickly approach the business end of the season.
A win is therefore a must today for new-look Pompey, who signed both Di’Shon Beranrd and Paddy Lane on transfer deadline day.
But how do the so-called data experts at FiveThirtyEight see today’s game at Fratton Park going and this afternoon’s other League One games?
Here’s what we discovered...

1. PETERBOROUGH, ENGLAND - JANUARY 28: Reeco Hackett of Portsmouth celebrates after scoring but it is disallowed during the Sky Bet League One between Peterborough United and Portsmouth at London Road Stadium on January 28, 2023 in Peterborough, England. (Photo by Catherine Ivill/Getty Images)
Reeco Hackett celebrates scoring for Pompey against Peterborough last weekend. Picture: Catherine Ivill/Getty Images Photo: Catherine Ivill

2. Accrington v Lincoln
Accrington win: 35%. Lincoln win: 36%. Draw: 29%. Photo: Bryn Lennon


4. Bristol Rovers v MK Dons
Bristol Rovers win: 38%. MK Dons win: 36%. Draw: 26%. Photo: Harry Trump