Barnsley's latest signing David Cotterill is expected to start on the substitutes' bench.
Winger Cotterill, 24, completed his move to Oakwell until the end of the season this week, but is short of match fitness following his release from Swansea last month.
Another recent signing, former Orient skipper Stephen Dawson (ankle), is hoping to be in contention for his first appearance and could also be included on the bench.
Defender Bobby Hassell sustained a knee injury in training this week and will be sidelined for a fortnight, but winger Jim O'Brien is pushing for his first start since Boxing Day.
He stepped off the bench in the midweek defeat at Burnley after recovering from a niggling groin injury.
Barnsley slipped to back-to-back away defeats last week and are 12 points adrift of the play-offs.
Portsmouth have an injury crisis.
Kelvin Etuhu sustained a hamstring injury and fellow midfielder Liam Lawrence picked up a calf problem during Tuesday's 1-0 home defeat to Ipswich and have joined three team-mates on the sidelines, leaving manager Michael Appleton with just 14 players at his disposal.
Veteran striker Kanu continues to struggle with a back injury and is unlikely to return against the Tykes.
Midfielder David Norris is still making his way back from a double hernia operation and forward Luke Varney is building up his fitness after two months on the sidelines with a knee injury.
Defender Ricardo Rocha (calf), Greg Halford (knee) and Joel Ward (hip) are also doubts. Appleton had spoken of his desire to rest Marko Futacs, but the ever-extending injury list is likely to see the striker occupying a starting berth again.
Youngsters Adam Webster, Sam Magri, Jed Wallace, Alex Grant and Dan Butler have been training with the first team and may be included in the squad to make up the numbers.
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