Town's preparations for Saturday's trip to Charlton have been disrupted by a flu bug which has hit several members of the squad, as well as boss Jim Magilton. Defender Fabian Wilnis, who was set to return in place of the injured Alex Bruce, and midfielder Gavin Williams are amongst those affected.
Boss Jim Magilton said: "There are four or five who are quite bad today. Fabian stayed at home and we will see how he is tomorrow.
"We will stay overnight in London and hope more are not affected. We have players on stand by to come down to London tomorrow if needed.”
Sito and Chris Casement will be in the squad as defensive cover with David Wright likely to move to centre-half if Wilnis fails to make it.
Town are already without Alex Bruce after he picked up a groin injury in the 2-0 defeat at Bristol City. The Republic of Ireland international may also miss the home game with Leicester City on Tuesday. Richard Naylor is also still sidelined due to his back problem.
Jason De Vos will continue in his usual centre-half role, while Casement has previously been picked ahead of Sito when Wright has had to move from right-back. Dan Harding will continue at left-back with Neil Alexander in goal unless they are amongst those struck down.
Magilton again faces choices in midfield even before the bug hit the squad, having switched things around at Bristol City. Jon Walters was used up front at Ashton Gate but could move back to his usual right-sided role, particularly if Williams is unable to play.
In the centre, Owen Garvan and Sylvain Legwinski were paired in midweek, but Tommy Miller will hope for some involvement at the Valley. Gary Roberts came in on the left against the Robins and picked up his fifth booking of the season, but serves his one-match suspension when Leicester are at Portman Road on Tuesday.
Magilton will again have to decide whether to use a 4-4-2 or a 4-5-1 formation, although his options in midfield may be limited by the illness situation. Alan Lee would start on his own in a 4-5-1 with Pablo Couñago probably joining him if the Town manager decides to employ two strikers.
Charlton currently sit in third place in the Championship table, but with a mixed record at home, having won four times, drawn twice and lost on four occasions.
Like Magilton, Addicks boss Alan Pardew has to decisions to make regarding whether to use 4-4-2 or 4-5-1.
Defender Grant Basey remains on the sidelines with a groin injury, while former Arsenal academy midfielder Jerome Thomas is back in contention after a dead leg.
Town's last game at the Valley came in the 2001/02 relegation season when the home side came back to win 3-2 after Marcus Bent, now a Charlton player, had put the Blues two-up after five minutes.
Overall, Town have had the better of the Addicks, winning 17 games between the two sides (13 in the league), drawing eight (seven) and losing 15 (12).
In addition to Bent, former Blues skipper Matt Holland and Darren Ambrose are also current members of the Charlton squad. Town's Danny Haynes was a schoolboy with the Addicks academy, before being released and joining the Blues youth set-up.
There will be no Town tickets on sale on the turnstiles but the Ticket Office had a few remaining restricted view seats as of this morning. Charlton expect their highest gate of the season.
Saturday's referee is Neil Swarbrick from Lancashire, who has shown 37 yellow and three red cards in 18 games so far this season. Swarbrick's last Town game was the 1-1 draw with QPR at Loftus Road in October when he booked only Rangers striker Rowan Vine.
Probable squad: Alexander, Supple, Wright, Harding, Wilnis, De Vos, Casement, Sito, Garvan, Miller, Legwinski, Williams, Roberts, Clarke, Walters, Lee, Couñago, Haynes.