Portsmouth are sweating on the fitness of Liam Lawrence .
The influential winger limped out of Saturday's 1-0 win over Barnsley with a recurrence of a calf injury and will undergo a scan to discover the extent of the problem.
Aston Villa loanee Jonathan Hogg returns from suspension and could come back in if Lawrence is ruled out.
Skipper Aaron Mokoena may have to make do with a place on the bench again with the defence having kept back-to-back clean sheets in his absence, although he could step into the midfield.
Kanu could earn a recall to the starting line-up after he came on as a second-half substitute to grab the winner against the Tykes.
Fellow striker Danny Webber (cruciate) is still out.
Crystal Palace will check on Alex Marrow ahead of the trip to Pompey.
The midfielder failed a late fitness check on an ankle problem ahead of Saturday's 1-0 win over relegation rivals Sheffield United and will be assessed before kick-off.
South Africa international Kagisho Dikgacoi impressed on his debut at the weekend after joining on loan from Fulham and should keep his place in the centre of midfield.
Nathaniel Clyne is playing despite an ongoing knee problem which has restricted his training and he should be okay to continue, but fellow full-back Lee Hills remains a long-term absentee with a knee injury.
The Eagles are also poised to complete the signing of 17-year-old midfielder Quade Taylor from non-league Dulwich Hamlet.