The 24-year-old suffered an ankle injury against Hull on Saturday and is awaiting the results of a scan.
Defender Matty Willock has been closing in on a return from a hamstring injury and could feature.
Ryan Jackson may also be involved having served the one-match suspension he received for collecting a red card during the Gills first-round success over Southend.
Coventry captain Liam Kelly could be absent after leaving the pitch with an injury during Saturday's 2-1 defeat to Bristol City.
The 30-year-old midfielder was replaced by Jordan Shipley in the 23rd minute at Ashton Gate.
The fixture comes too soon for winger Wesley Jobello, who is expected to rejoin training soon after suffering an anterior cruciate ligament rupture last October.