Poulsen headed a clearance into the back of team-mate Daniel Agger and it bounced past goalkeeper Thomas Sorensen to break the deadlock in the Group E contest at Soccer City.
The AZ Alkmaar defender has been forgiven by his team-mates but that has not really helped him in the intervening period. "I have thought about it a thousand times," said Poulsen.
"Of course, I have tried to think about all the positive moments in the match, and I think the team and myself played a good first half. Yet the [own] goal keeps coming back. I have seen it on TV, and it's really unfortunate."
Arsenal striker Nicklas Bendtner did not take part in the team's training session today, remaining at the squad's hotel for physiotherapy. He was replaced after an hour of the first game with a groin injury.