Samoa came from behind to beat New Zealand 24-21 and win the Hong Kong Sevens Sunday, taking the lead in the IRB Sevens World Series with two tournaments left in the season. Samoa's third straight title, which came at the biggest event of the year, gave it 30 points and an overall 124 points in the standings. New Zealand dropped to second with 121 points. Earlier, Samoa beat the US 24-7 in the quarterfinals and edged England 28-24 in semis . Australia defeated South Africa 12