Paul Cook is weighing up changing a Pompey side which were so disappointing against Doncaster.
With no fresh injury worries, the Blues boss must decide whether to freshen up his team following successive league defeats.
Milan Lalkovic and Kyle Bennett featured in the Checkatrade Trophy in the week and will challenge Kal Naismith for a starting spot.
Curtis Main also delivered a timely reminder with two goals in that 2-2 draw.
Adam Buxton is out with an injured ankle, while Noel Hunt (groin) and Drew Talbot (hamstring) are missing.
For Leyton Orient, Nigel Atangana could make his injury return against Pompey.
The former Blues midfielder has been sidelined with a groin problem, but is pushing to make his Orient comeback this weekend.
Definitely missing is Robbie Weir, who is serving the second of a three-match ban following a sending off.
Jens Janse is also suspended, after a red card on his debut.
Ex-Pompey player Paul McCallum will partner Jay Simpson in attack, looking to build on the six goals he has so far netted this season.