The 12-goal striker, on loan from Watford until the end of the season, sustained a nasty ankle injury which forced him off towards the end of the impressive 3-0 win at Dagenham on Boxing Day.
Assombalonga will now receive treatment and be given every chance of being fit for the Pirelli Stadium clash.
Skipper Chris Barker recovered from an ankle knock of his own to start against Dagenham, meaning manager Paul Sturrock was able to again name an unchanged starting XI.
However, Sturrock has not ruled out rotating his squad as they prepare for a further two games in four days, with the fourth-placed Shrimpers - unbeaten in 14 matches - at home to leaders Gillingham on New Year's Day.
- Sports & Recreation
- Paul Sturrock