Boss John Mousinho has some big decisions to make both over formation, after playing a back three at Fleetwood, and whether to start the likes of new boy Myles Peart-Harris after his arrival from Brentford.
Here’s how we think the Blues will go at Vale Park.
1. GK: Will Norris
A 13th clean sheet at Fleetwood for one of Pompey's standout performers of the season. Photo: Jason Brown
2. RCB: Conor Shaughnessy
Touch and go over Joe Rafferty's fitness. If the Scouser doesn't make it, the likelihood would be continuing with back a three and Shaughnessy on the right. If Rafferty is announced as being fit, the probability would be a move to a back four. Photo: Jason Brown
3. CB Sean Raggett
Looked rock solid dealing with Jayden Stockley last weekend and left the ball-playing stuff to his defensive partners. Photo: Jason Brown
4. LCB: Ryley Towler
A lot depends on Rafferty to whether Towler starts. Was steady enough last weekend, but could conceivably find himself out of the squad if the right-back returns. Photo: Jason Brown