Martin Guptill continued his rich run of form as he scored 78 not out to help New Zealand to a six-wicket victory over South Africa in their Twenty20 International at Wellington Regional Stadium Friday. Guptill anchored the New Zealand run chase as the hosts scored 148-4 in 19.2 overs after South Africa had scored 147-6 in 20 overs with JP Duminy scoring 41. The 25-year-old Guptill had plundered the much weaker Zimbabwean attack in the first series of New Zealand's summer, scoring 232 runs at 77.33 in the three One-Day Internationals before he smashed 91 not out in his only Twenty20 appearance. On Friday the opening batsman took on a much stronger attack and hammered four sixes in his 55-ball innings, including two in one Lonwabo Tsotsobe over that went over 100 metres. The second actually hit the roof of the stadium and was measured at 127 meters on the fly. James Franklin belted the winning runs with a four to the cover boundary with four balls remaining to give the hosts a 1-0 lead in the best of three series. New Zealand's bowlers had contained the South African batsmen, though Justin Ontong belted off-spinner Kane Williamson for four successive sixes as the visitors took 26 runs off his second, and last, over. Ontong (32) had combined in a 50-run partnership with Duminy though both fell to Tim Southee.The second match is on Sunday in Hamilton.