Ireland pulled off yet another Cricket World Cup upset on Monday when it raced to 307-6 to beat two-time champion the West Indies' by four wickets with 25 balls to spare in a Pool B match, taking a giant stride toward the tournament's quarterfinals. Paul Stirling ignored the ball that clattered into his visor early in his innings to make 92, then Ed Joyce took up the chase and made 84 as Ireland surpassed the West Indies' total with 21 balls, becoming the first team at the tournament to win while batting second. Finally Niall O'Brien made an unbeaten 79 from 60 balls to complete the job, holding his composure during a late flurry of wickets which saw Ireland slip from 273-2 to 291-6 and set Irish hearts racing. "It's obviously fantastic," Ireland captain William Porterfield said. "The way we set about chasing those runs was great and it sets us up now for the next few games. It's a great position to be in. "The self-belief has been growing in the squad for a long time and we thoroughly believed when we went out on the pitch today that we were capable of winning this game and not only this game other games in the competition and we've just got to continue that now throughout the tournament." Stirling and Joyce were members of the Ireland team that beat England in a famous upset at the 2011 World Cup, building on Ireland's giant-killing reputation which had been forged when it beat Pakistan during its first World Cup appearance in 2007. There have been only six occasions in 11 World Cups in which a team has won chasing more than 300 and three of those victories belong to Ireland. The match marked the first appearance at this tournament of an associate team - one of cricket's non test-playing nations - and delivered a stern rebuke to the International Cricket Council which will attempt to shut those teams out of the next World Cup by limiting entry to 10 teams. Ireland's victory was achieved with such a calm professionalism that it was hard to tell which was the top-eight team.