Victory against the Bluebirds - one of the Blues’ main relegation rivals - will set the tone for a crunch set of fixtures that immediately lie in wait and could determine the club’s Championship fate.
Anything other than that at P04 - a place where John Mousinho’s side have enjoy plenty of success in recent months until Millwall’s visit two weeks ago - will pile the pressure on Pompey and give those around them in the lower reaches of the division hope that they can overcome their own relegation struggles.
The team Mousinho puts out against 19th-placed Cardiff will be imperative. Last Saturday’s trip to Sheffield United saw the head coach name an unchanged side to the one that drew 0-0 with Burnley. That surprised many of the Fratton faithful. So the questions is: will he do the same tonight after the Blues produced their best performance of the season at Bramall Lane - despite the defeat? Or will he make changes to his side in areas that could possibly need fresh legs?
Here’s how we think Pompey could line up against Cardiff, with a key decision taken on one of the Blues’ six loan options - Isaac Hayden.
5. Centre-back 2 - Rob Atkinson
The on-loan Bristol City defender is proving a shrewd bit of business by the Blues. Continues to grow in strength and presence at the heart of Pompey's back line and is already forming a good partnership with Shaughnessy - which bodes well. | National World
6. Left-back - Conor Ogilvie
After a shaky start to life in the Championship, Ogilvie is suddenly playing himself into player-of-the-year contention with his consistent, top-quality performances. | National World
7. Central midfield 1 - Andre Dozzell
The January transfer window arrival of Isaac Hayden was meant to reduce the former Ipswich and QPR man to more time on the sidelines. It hasn't worked out that way, though, with Dozzell rising to the challenge and proving his worth in the Blues engine room. | National World
8. Central midfield 2 - Freddie Potts
The on-loan West Ham youngster remains a consistent performer for the Blues. Competition for places in the Pompey engine room has intensified following the loan arrival of Hayden and Marlon Pack's return to midfield duties. Mousinho could be tempted to rest Potts tonight, but he gets into our starting XI for the visit of the Bluebirds. | National World