Barnsley have not appealed the red card for Mael de Gevigney on Tuesday so he will miss the next three games.
The Frenchman was sent off for a tackle on Tariqe Fosu in a 2-1 win at Northampton Town.
The defender will miss Lincoln at home on Saturday, Charlton away on Tuesday and Blackpool at home the following Saturday.
He could be replaced by Conor McCarthy who came off the bench in midweek following the red card, unless the Reds change formation to a back four.
Head coach Darrell Clarke said: “He’s obviously dived in. Mael is an honest lad.
“We won’t get that overturned. The referee was very quick to get the red card out. He’s off the ground. We have to take our medicine on that and move on.
“I could go for a three or a four at the back. Time will tell.”
Meanwhile, Jonathan Lewis is out with a thigh problem.
The American, who joined earlier this month and has played once off the bench, felt some discomfort in the warm down on Saturday.
“The scan came back with a little tear, he will be a few weeks.
“It’s a frustration but we have to go on with it.
“We have seven or eight players out with injuries or suspensions but we will rock and roll with it.
“No excuses. Players need to come in and take their opportunities and continue our good week.”