Cheltenham manager Mark Yates says Jason Taylor's first-half red card "ruined" Tuesday's game with Southend.
Midfielder Taylor was sent off on 37 minutes after tangling with Conor Clifford, who scored the only goal of the game for the visitors.
It was the first red card the Robins have received since former captain Alan Bennett's dismissal against Fleetwood in October 2012.
"The game was ruined by the official," Yates told BBC Radio Gloucestershire.
"Our supporters are the most mild-mannered supporters in the world. For them to give the referee what they gave him throughout the game, and at the end, proved there was something up.
"I don't want to say any more, as I'll only get myself in trouble."
Yates then confirmed he had asked to speak to referee James Linington after the game regarding the incident.
The game was goalless before transfer-listed midfielder Taylor and Southend's Clifford became involved in a scuffle after a tackle from the Robins man.
The visitors went on to inflict a second consecutive defeat on Cheltenham, who dropped to eighth in the table.
"I saw it at half-time and I thought it was very harsh but Taylor has given him the chance [to send him off]," added Yates. "I don't think there's anything we can do about it. He shouldn't have bothered grappling with him."