Pompey travel to Peterborough tomorrow with the stakes high in the League One promotion showdown.
Mousinho has fitness and injury issues to contend with, as he's tasked with blunting the division's more potent attacking force.
And then there is the big talking point of who starts up front out of Kusini Yengi and Colby Bishop?
What does Mousinho do in terms of formation, too, after switching to a back three against Burton on Tuesday night?
Here's how we think the Pompey boss will go against Darren Ferguson's side.
17. Sub 5: Josh Martin
Out of and Martin and Whyte for back-up winger berth. | National World
18. Sub 6: Christian Saydee
Likely to be sacrificed through no fault of his own, as Pompey stiffen up the side at London Road. | Jason Brown/ProSportsImages
19. Sub 7: Colby Bishop
Could well start, but certain to play some kind of role in the afternoon's events. Photo: Bryn Lennon