In Ireland's opening game of the 2004 Six Nations Championship, O'Connell captained the side in the absence of Brian O'Driscoll. He also played in the game against Scotland on 27 March 2004, in which Ireland won their first Triple Crown for 19 years. O'Connell also gained silverware on the club front when Munster won the last final of the Celtic Cup, defeating Llanelli Scarlets 27–16 in Lansdowne Road on May 14, 2005. He was also part of the Ireland team that won a Triple Crown in the 2006 Six Nations Championship, playing in a dramatic 24-28 victory over England to clinch the Crown. He scored the last International try at the Old Lansdowne Road before it was demolished and rebuilt as the Aviva Stadium, in a 61-17 victory over the Pacific Islanders.