Colchester winger Ashley Vincent is a major doubt for the visit of Charlton as he awaits the results of a scan on his left knee.
Vincent broke the deadlock in Saturday's 1-1 draw against Wycombe before being forced off just before half-time having twisted his knee.
Although the extent of the problem is not yet clear, it is almost certain the wide man will not feature against the Addicks.
Manager John Ward does have options, however, in Steven Gillespie - who stepped up his recovery from a groin problem by replacing Vincent at the weekend - Ben Coker and Lloyd James.
Midfielder Andy Bond (head) and goalkeeper Ben Williams (viral infection) are back in training and pushing to be in contention.
But midfielder Jordan Sanderson (foot) continues to miss out.
Charlton manager Chris Powell could face a goalkeeping dilemma.
Rob Elliot has started the first two games of the season despite stalling on a new contract, but summer signing Ben Hamer is close to recovering from a hand injury.
Powell could otherwise stick with the line-up which has picked up a maximum six points so far.
That would mean former Dagenham winger Danny Green having to wait for his debut as Scott Wagstaff has scored two in two games and is set to keep his place.
Striker Paul Benson will hope to make the bench after losing his place in the squad to the re-signed Jason Euell at the weekend.
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