O'Connell made his debut for Ireland against Wales in the 2002 Six Nations Championship, starting alongside Mick Galwey and scoring a try. Despite scoring this try, O'Connell has no recollection of the first half, recalling: "I scored a try but I don't remember it. I went to tackle Craig Quinnell and he knocked me clean unconscious with his elbow. I played on for another 25 minutes, scored a try and then, eventually, with seven minutes left in the first half, I came around. I didn't really know what was going on and so I walked off the pitch."