A mix-up between Wojciech Szczesny and Laurent Koscielny gifted Obafemi Martins the winner in Birmingham's 2-1 victory over the Gunners in the Carling Cup final.

Although Arsenal are still fighting for honours in the Barclays Premier League, the FA Cup and the Champions League, yesterday's final was seen as the best chance for the club to win a trophy this season.

Arsenal manager Arsene Wenger admitted Koscielny and Szczesny were "destroyed" by the error, but Rosicky insists the club must forget the incident quickly, starting with Wednesday's FA Cup fifth-round replay against npower League One side Leyton Orient.

"The big games are decided by who makes the most mistakes, and we made the big mistake," Rosicky told Arsenal TV Online.

"Obviously we are very disappointed but we have to pick ourselves up immediately. We have a game on Wednesday so we have to perform.

"The season doesn't finish now. We are still in a good position in other competitions so we have to quickly try to forget this and concentrate on other stuff.

"It's very important to go through to the next round. We have to try to forget about this and move on."

Arsenal's misery at losing was compounded by the news that Robin van Persie picked up a knee injury while scoring the equaliser after Nikola Zigic headed the Blues ahead.

The Dutchman, who was making his comeback from a hamstring injury, is being assessed by the club's medical staff today, with Wenger desperate for his star striker not to miss next week's Champions League clash with Barcelona.

The Gunners are currently in the middle of a gruelling schedule that will see them play eight matches in 24 days and the Arsenal boss thinks that may have played a part in yesterday's loss.

"We were a bit jaded at the start because we have played so many games," the Frenchman said.

"Sometimes it's hard to get into your rhythm but in the second half we were in control.

"It's a massive disappointment because we produced the performance we wanted.

"It looked like we were going to win the game but I feel we missed a bit of sharpness and the number of games that we are playing played a part."

Wenger echoed Rosicky's call for the team to bounce back and insists the team, who are just four points behind league leaders Manchester United with 11 matches left, are still capable of winning trophies this season.

He said: "It's disappointing to concede a goal like that. What was terrible about that mistake was that we had no time to respond or change it.

"We are very, very disappointed but through that disappointment we don't want to miss the rest of the season.

"We have massive challenges in front of us. The team were unlucky but they will not be unlucky for the rest of the season.

"It is important that the whole team responds in the right way on Wednesday."