Bladed defender Tony McMahon is hoping to make his first appearance of the season this weekend.
McMahon has recovered from a sprained ankle, the latest in a succession of injuries, and is expected to be included among the substitutes.
Manager David Weir must decide on who to fill the void left by departed midfielder Kevin McDonald, who joined Wolves this week for an undisclosed fee. Jamie Murphy was recalled at Brentford, but Callum McFadzean is also pushing for a start.
Weir, who has no new selection problems, could be tempted to recall striker Chris Porter, while wide midfielder Ryan Flynn is hoping to make his first league appearance of the season.
Colchester boast a fully-fit squad for their trip to Yorkshire.
The U's travel to Bramall Lane defending a 100 per cent record in League One following 1-0 victories over both Gillingham and Port Vale.
Forward Sanchez Watt recovered from a leg injury to make his first start of the season against Vale last weekend, with Marcus Bean dropping to the bench.
Bean has fully recovered from the virus which affected him in training last week and will compete with Watt for a starting berth against the Blades.