Carl Baker has seen his appeal against Tuesday's red card at Leyton Orient rejected and will now serve a three-match suspension.
The midfielder was sent off early in the second half of the 3-2 Capital One Cup defeat following a late challenge on Romain Vincelot.
City appealed against the decision but it has been unsuccessful and Baker will now miss Sunday's game against Bristol City as well as the fixtures versus Preston and Carlisle.
This weekend's meeting with the Robins is Coventry's first 'home' fixture at Sixfields Stadium as they prepare to groundshare with Northampton for the next three years while their proposed new stadium is built.
The move - which comes after a lengthy rent row with Ricoh Arena management company Arena Coventry Limited (ACL) - has not proved popular with City's protesting fans, who appear to have voted with their feet ahead of Sunday's Sky Bet League One clash.
Approximately 500 season tickets have currently been sold, compared to around 5,700 last summer when playing at the Ricoh Arena, while just 200 or so matchday tickets have been purchased in advance as of Thursday morning.
City's average attendance last season while playing at the Ricoh was almost 11,000.
In fact, a far greater number of Sky Blues supporters are expected to attend a Coventry City Former Players Association charity match at the Ricoh Arena on Sunday, as they again show their opposition the groundshare.
The event, which organisers hope will attract a crowd of close to 10,000, sees a CCFC legends side take on a midlands all stars team.