A mistake by goalkeeper Jens Lehmann cost Arsenal two points against Blackburn as the match finished 1-1 at Ewood Park.
Sloppy defending by the home side allowed Robin van Persie to score his second of the season in the 18th minute.
However in the 72nd minute Lehmann allowed a routine shot from David Dunn to slip through his grasp.
The Gunners where then unable to take advantage of the late dismissal of Rovers defender Ryan Nelsen as both sides shared the spoils and retained their unbeaten starts to the season.
A feisty encounter saw seven yellow cards from referee Alan Wiley and a red for the New Zealand international.
Gunner boss Arsene Wenger felt it was a case of two points dropped.
"We feel we have dropped two points because we were 1-0 ahead and had a few chances to score a second goal."
"Before we conceded it was not obvious they would score, so that is why we are frustrated.
"But it was a good performance. We were resilient and dealt well with the long ball and the physical challenge they gave us."
"He feels very down at the moment because of course he knows his responsibility," said Wenger.
"A goalkeeper is there not to make mistakes and he will certainly be concerned, but what we have to worry about at this stage is to just prepare for our next game."
Arsenal remain unbeaten this season and Wenger added: "It is a decent start and we have the ingredients to have a lot of hope."