Pompey are just a point ahead of John Hughes' side and are on a club record winless run of 19 games.
If they are to avoid dropping to the foot of the table it will be without striker Connolly, who remains sidelined with a hamstring problem.
John Akinde and Patrick Agyemang, who both made their debuts against Bournemouth at the weekend, will continue in attack.
Bos Guy Whittingham also allowed youngster Frankie Sutherland to return to parent-club QPR after he failed to break into the first team at Fratton Park.
He made just one substitute appearance during his time at the club - against Hartlepool - and he will not be involved against the same opponents after his stay was ended early.