Oxford United manager Chris Wilder says his side's discipline must improve if they are to maintain their push for a play-off place this season.
The U's had Damian Batt red carded in the 39th minute of their 2-1 defeat by Bradford on Saturday.
It was their second first-half red card in three games, following James Constable's dismissal against Swindon.
"We cannot keep getting players sent off, it's ridiculous," Wilder told BBC Radio Oxford.
Batt was booked in the sixth minute for a lunge on Kyel Reid, and he received a second yellow for a foul on the same player before the break.
"I thought it was a really spirited performance, especially as we went down to 10 men," he said.
"I disciplined Beano (James Constable) last week even though we got a result.
"The players are shattered out there. We've had to play 50 minutes with 10 men and it was a poor decision by Damian.
"He has come in and apologised and rightly so.
"He's up against a decent player in Reid but he's gone flying in and rightly got a booking and that is after five minutes. He puts himself under pressure.
"We do our homework and knew Reid is a good player. You've got to do your job against good players and be patient, but he was reckless."