Sunderland manager Regis Le Bris believes Trai Hume's red card was "harsh" made it tough for his side in their 2-1 loss at Bristol City.
Hume was dismissed on seven minutes for bringing down Nahki Wells as the last man before Robert Dickie and Ross McCrorie won the game following Eliezer Mayenda's opener.
The Black Cats have already secured a play-off place but Le Bris was frustrated by the decision despite praising his side for their reaction.
"It was a harsh decision from the referee. We have to accept it," he said, speaking to BBC Radio Newcastle.