Pompey will be without Marcos Painter when they host Chesterfield.
The defender, recently signed from Brighton, suffered a hamstring injury during last weekend's 2-2 draw at Mansfield and faces a couple of weeks on the sidelines.
Yassin Moutaouakil came on to replace Painter, with Joe Devera switching from right to left-back, but Dan Butler or Danny East will also be in the frame to step in.
Winger Ricky Holmes, who has made three substitute appearances since recovering from a foot injury, is pushing to make his full debut following his summer switch from Barnet.
Ian Evatt could be included in the Spireites squad for the first time this weekend.
Former Spireite Evatt rejoined the club last month but has yet to feature for the first team as he regains full fitness following nine months out after knee surgery.
But the defender, 31, manager Paul Cook's captain-in-waiting, has played in two behind-closed-doors friendly matches in the past 11 days and Cook feels he is now ready to be considered.
Fellow centre-half Matty Brown is the only injury absentee as he recovers from a hamstring problem.