Shrimpers boss Phil Brown will check on Ben Reeves and Luke Prosser as he prepares to take charge at Roots Hall for the first time.
The former Hull City manager will be looking to bounce back from the disappointment of seeing his new side throw away a two-goal lead at Bradford on Friday as he took the reins following Paul Sturrock's departure.
Brown could be without midfielder Reeves and defender Prosser as the hosts look to leapfrog their opponents in the table.
Reeves came off at half-time on Friday after picking up a calf problem while Prosser suffered a knock.
Defender Chris Barker (Achilles), midfielder Michael Timlin (broken leg) and striker Neil Harris (knee) are definitely out while Mark Phillips (broken toe) is unlikely to feature despite returning to training.
The Cod Army could unleash top scorer Jon Parkin for the Easter Monday encounter.
Parkin came on for the last half hour of Saturday's entertaining 2-2 draw against league leaders Gillingham, with bench duty a possible precaution taken by boss Graham Alexander amid the hectic fixture schedule as persistent hamstring injuries have plagued the well-travelled striker this term.
Alexander must weigh up the enticing prospect of pairing Parkin with record signing Jamille Matt in attack.
Matt initially struggled to adapt to life at league level following a January move from Kidderminster but continued his transition with both goals against the Gills.
Andy Mangan provides another forward option and will hope for further game time from the bench after a late weekend cameo ended his six-month knee injury absence.
Defenders Rob Atkinson and David Howell are set to miss out once more due to respective groin and leg problems, while forward Steven Gillespie (hamstring) is back in training but is expected to be absent again.
Veteran midfielder Paul McKenna provides an option should Alexander wish to shuffle his pack after returning from suspension to be an unused substitute on Saturday.