Oldham caretaker manager Tony Philliskirk has a trio of fresh fitness problems to concern himself with.
The Latics moved out of the relegation zone with a 2-1 comeback win at Stevenage in midweek but victory came at a cost as midfielders Carl Winchester and James Wesolowski sustained injuries, along with defender Cliff Byrne.
Winchester left the Lamex Stadium in a protective boot and on crutches after suffering an ankle injury which is not as serious as first feared.
Nevertheless, he is expected to miss out against Pompey along with Wesolowski (hamstring), Bryne (groin) and long-term injury victims Cristian Montano (thigh) and Youssouf M'Changama (knee).
Philliskirk made six changes to his starting XI against Boro following Oldham's exertions in the 2-2 FA Cup fifth-round draw against Everton and may shuffle his pack again, although club captain Dean Furman is expected to keep his place in central midfield after scoring the equaliser on Tuesday.
Portsmouth will be without Shaun Cooper.
The on-loan Crawley defender suffered a hip injury during last weekend's 1-1 draw against Carlisle and will be missing for around a fortnight.
Former Charlton full-back Yassin Moutaouakil is poised to come in for Cooper in what is likely to be the only change to caretaker boss Guy Whittingham's starting line-up.
But veteran striker David Connolly could be added to the bench after three weeks on the sidelines.
The Irishman has missed the last four matches with a hamstring problem but has this week returned to training.
Pompey have slumped to the bottom of the table despite successive draws and are still without a win since October 20.