There’s a number of key issues for the Blues boss to consider, in a number of different areas of the pitch.
Are Regan Poole and Conor Shaughnessy ready to feature in the middle of the back line? Does Millenic Alli continue after a drop in form? Who plays in the No10 position? And does Mousinho keep faith with Colby Bishop?
Our Pompey writer Jordan Cross has weighed up the talking points - this is how he thinks the Pompey head coach will go.
9. RW: Gustavo Caballero
Form has fluctuated as he adapts to English football, but Paraguayan looks to be the front-line option for the right flank. | Simon Roe/ProSportsImages
10. CAM John Swift
Now this is a big call. Looks like one from four with Swift, Chaplin, Segecic and Brown the options. It was Swift who central to the last wins at Millwall and Charlton in the position, so gets the nod on that basis. | Graham Hunt/ProSportsImages
11. LW Millenic Alli
Has to be concerns over Alli's form dip over the past three games, given his previous importance and the loss of Josh Murphy for the season. A big game's needed. | Simon Roe/ProSportsImages
12. CF Colby Bishop
Even if the goals are coming, the Colby Bishop who gave Millwall and Charlton defence's a battering would be well received. | Simon Roe/ProSportsImages