The 24-year-old made what should have been a dream start to his international career, scoring the second of his side's six tries after being driven over direct from a line-out.
Unfortunately, the elegant Munster second-row has no memory of the game at all. Caught in the head by a stray elbow early in the contest, O'Connell eventually had to be helped from the field after half an hour and missed the following two games with concussion.
"When I came off the doctor told me I had scored a try but I thought he was just trying to calm me down and cheer me up a little bit because I couldn't remember a thing," he said.
"It was only when I saw the try on TV in the medical room at half-time that I realised he wasn't joking.
"We must have practised a thousand line-outs during the week but I couldn't remember a single call. I just jumped and caught it and the forwards did the rest.
"It was a strange day but these type of things happen in rugby and fortunately it's the only time I have ever been concussed."
It was almost 18 months before O'Connell started another game for Ireland but, after opting to stay on last summer's tour for the potentially hazardous trips to Tonga and Samoa, he performed sufficiently well to cement a place in coach Eddie O'Sullivan's first-choice World Cup line-up and is now virtually an automatic choice.
Unlike most observers, O'Connell claims he is not surprised about Wales' stunning form reversal and is anticipating one of the closest games of the championship this weekend.
"I'm not shocked about how well they are doing now," he said. "I was probably more surprised at how far they dipped beforehand.
"They were always going to come good in the end and after their win over Scotland, I'm sure they will head to Dublin full of confidence."