Left winger Belhadj is out with a hamstring problem, while respective back and groin injuries account for midfielder O'Hara and central defender Ben Haim. Full-back Steve Finnan returns to the squad but will have to settle for a place on the bench as teenager Lenny Sowah keeps his starting spot.
Portugal defender Ricardo Rocha is also back in contention while Frederic Piquionne leads the attack after missing last weekend's defeat to Aston Villa after being stranded in France.
Long-term absentees Hermann Hreidarsson and Danny Webber are also out but striker Aruna Dindane has been given permission by Lens to play out the remainder of the campaign.
Portsmouth (from): James, Ashdown, O'Brien, Mullins, Finnan, Rocha, Mokoena, Sowah, Vanden Borre, Wilson, Yebda, Brown, Boateng, Diop, Smith, Ritchie, Kanu, Utaka, Piquionne, Dindane, Ward.