Arsene Wenger Wenger believes indiscipline will not let Arsenal down in their big Sunday showdown against Manchester United at Old Trafford.
Clashes between the two sides have been bad tempered in the past and the Gunners go into the game with Alex Song, Gervinho and Emmanuel Frimpong suspended.
Wenger, whose side have just one point from their first two Premier League matches, said: "The discipline has cost us a lot since the start of the season. If we had mastered our responses and reactions we could have six points. It's even more important to get results and not let Manchester United away too early. It is vital for us to have a good game on Sunday."
He added: "Sometimes at the beginning of the season it is like a Western film, they (the players) come out stronger. But we have shown that we have mental strength and good unity to fight. I'm confident we will be solid on Sunday and have a big performance."
Wenger believes the midweek triumph against Udinese in the Champions League qualifying tie has given his side the feelgood factor.
He said: "After the first game with Udinese I felt the squad was a bit insecure. That game was in our mind when we played Liverpool. That game is out of the mind now and we have a much more convincing team at Manchester."
Wenger's squad, however, still looks light on numbers with Cesc Fabregas and Samir Nasri having been sold, Jack Wilshere still recovering from an ankle problem and Sebastien Squillaci, Kieran Gibbs, and Abou Diaby sidelined with injuries while Nicklas Bendtner looks set to leave the club despite also suffering from an ankle knock.
Wenger hopes to bring in reinforcements before the transfer window shuts next week, although an offer for Bolton defender Gary Cahill has been described as "derisory" by the north-west club.
Bolton say the offer is Â£6m, a figure which is disputed by Wenger.
"That number is wrong," said Wenger. "It is completely wrong. Every negotiation is between two parties and you only have to sell the player if you are all right with the price. In this case the information is below what has been spoken about."