Leinster Under-21 Hurling Championship Once a team is defeated they are eliminated from the championship. The Leinster Championship has wider implications for the All-Ireland Under-21 Hurling Championship. The winners of the Munster final automatically qualify for the semi-final stages of the All-Ireland series of games. Unlike the final runners-up in the minor and senior championships, there is no 'back-door system' at under-21 level. Eight of the twelve counties of Leinster – Carlow, Dublin, Kildare, Kilkenny, Laois, Offaly, Westmeath and Wexford – participate in the championship. At the end of the Leinster final, the winning team is presented with a trophy. The cup, named the
2018 All-Ireland Senior Hurling Championship four matches, with Carlow confirming their place on 9 June after beating Westmeath. The top two teams at the end of the round-robin, Westmeath and Carlow, faced each other in the final on 1 July 2018. The game, which took place in Croke Park, saw Carlow emerge victorious by a margin of five points to claim the inaugural Joe McDonagh Cup title. As a Leinster county, Carlow were automatically promoted to the Leinster championship for 2019, taking the place of Offaly. The preliminary quarter-finals saw the third-placed teams from the two provincial round-robins play the two teams who competed in