The White Ferns face a must-win against Ireland to keep their T20 World Cup hopes alive.The White Ferns’ defence of their Twenty20 World Cup crown hangs by a thread after a second straight defeat to begin the tournament – losing to Sri Lanka by five wickets in Southampton.And once again it was dropped catches that proved costly.New Zealand now must win their three remaining pool matches and hope results go their way with just the top two teams advancing to the semi-finals.They next face Ireland and Scotland, which they should go in as favourites, before ending pool play against hosts England at the Oval. Much like the opening defeat to the West Indies, New Zealand set a fairly strong target finishing with 150 for six with Amelia Kerr (45 from 36) and Sophie Devine (45 from 30) doing the majority of the scoring.Sri Lanka started strong in their chase reaching 45 for the first wicket before New Zealand started to make in-roads. First Bree Illing bowled skipper Chamari Athapaththu for 27 before Nensi Patel struck twice between a run out by Amelia Kerr to see Sri Lanka fall to 55 for four. But the White Ferns couldn’t finish them off. Sri Lanka’s number six batter Nilakshika Silva scored a match-winning 54 from 37 balls with some help from Kaushini Nuthyangana (24 from 14) to chase down the total with two balls to spare.It was a familiar story in the field for the White Ferns after a disappointing effort in the opening game with Silva dropped on one by Illing at short fine leg - before the Sri Lankan went on to led her side to victory. Georgia Plimmer also shelled a fairly simple chance early in the Sri Lanka innings.“We had enough runs, but today, it was again the fielding that let us down,” captain Kerr said after the defeat.“Still three games to go, three games for our country that are important. We have to pick ourselves up. We are in a good place [batting and bowling] but that is two games in a row, we have not been up to a high standard [in the field].”The White Ferns remain in Southampton where they will play Ireland on Saturday morning NZT.