The club's top scorer picked up a fifth caution of the campaign during Saturday's 2-1 defeat against Yeovil and serves a one-match ban.
McLeod was replaced at half-time following an ineffective performance and his replacement Ashley Harris could be handed a start against the promotion-chasing Robins.
Skipper Brian Howard will be assessed ahead of the game as he too was substituted at half-time after complaining of a groin problem.
Experienced defender Jon Harley is available for selection after sitting out his one-game suspension against Yeovil and is expected to return to the defence.
Pompey have gone 12 games without a win and are in 21st place in the table, two points adrift of safety.
- Sports & Recreation