Arsene Wenger has called for his players to maintain their behaviour for 90 minutes on Sunday to avoid a red card against Tottenham.
Laurent Koscielny was sent off in Arsenal's opening Premier League game against Aston Villa while Emmanuel Adebayor's dismissal in last year's north London derby was arguably a contributory factor in the Gunners' 5-2 win.
"The game lasts 90 minutes and the behaviour of the players has to be focused and normal for 90 minutes," said Wenger at his pre-match press conference.
"[Koscielny] didn't deserve to be sent off and nobody cared about it, nobody asked what would have happened if Koscielny had stayed on"
"It is very difficult to predict what would have happened if Adebayor had stayed on. That [red cards] is part of the game.
"We played against Aston Villa with 10 men, [Koscielny] didn't deserve to be sent off and nobody cared about it, nobody asked what would have happened if Koscielny had stayed on. Certainly we would not have lost the game. But that is one of the decisions of the referee."
The north London derby takes place a day before the transfer window closes and Wenger remains confident of adding to his squad.
"Yes [I am active]," he said. "I am confident [but] I don't know [when things will be done]. We will not panic buy, that is for sure. You can believe me, it is not in my strengths to panic."
Tottenham have been busy in the transfer market but Wenger is only concentrating on his own club.
"I must confess I am not too much worried about their risk and what they do," he said. "I believe you win games when you focus on yourself and the quality of our game.
"The only thing that counts in football - I can understand that it is very interesting for people to read the newspapers and see who goes in and out - but there is only one thing that if you really love football, is what happens on the pitch.
"When you see our team play, I think that is the most important: what happens on the pitch. We have a way to play, we have good players and let's focus on that."