Oxford boss Chris Wilder was unhappy after James Constable's red card took the shine off his side's 3-0 win over AFC Wimbledon.
Goals from Sean Rigg, Alfie Potter and Tom Craddock did the damage as Oxford extended their unbeaten run to nine in all competitions.
After that Constable saw red for an apparent elbow on Wimbledon's Will Antwi, much to Wilder's chagrin.
"The ref got it wrong. The lads conned the referee and he's fallen for it hook, line and sinker," he said.
"There was a bit of a coming together and bit of banter between which, when I played, happened all the time. You were always winding players up and it's part of the game. All they were doing was having a nip at each other. The referee was sucked in.
"It is disappointing because it was a really good performance away from home. There was a lot of good individual performances and a brilliant collective performance too. It's another win and we're a bit closer to where we want to be.
"But I've lost a player who's absolutely flying for four big games now. I can't afford to lose anyone. We're gutted. A report and an appeal will go in 100 per cent.
"It's just ridiculous because you want to see the game played in the right way."