EAST LONDON: A brilliant, unbeaten century from opener Martin Guptill led New Zealand to an eight-wicket victory off the final ball against South Africa in the second T20 international on Sunday.

Chasing 169 for victory in 19 overs at Buffalo Park, Guptill helped erase the memory of Friday's embarrassing capitulation to 86 all out in Durban with a stunning batting display as the tourists reached their target for the loss of just two wickets to level the series 1-1.

Requiring 39 from the final four overs and 11 off the last, Guptill was on 97 and needing four for victory when Rory Kleinveldt bowled the final delivery - a low full toss which was eased away through extra cover.

Guptill's unbeaten 101 was just the third T20 international century by a New Zealander, the first two belonging to captain Brendon McCullum who was almost anonymous with 17 from 15 balls during a second-wicket partnership of 73 with Guptill.

The right-handed opener was similarly dominant during an opening stand of 76 with Rob Nicol (25) as he drove the Proteas attack impeccably straight and displayed the skills - and patience - so obviously missing from the New Zealand batsman in Durban.

Captain Faf du Plessis led from the front once again as South Africa posted a competitive 165-5 in 19 overs after losing the toss and being asked to bat first.

Du Plessis paced his innings to perfection on a tricky pitch to reach 63 from 43 balls with eight fours and a six in a match reduced to 19 overs per side following a 52-minute floodlight failure.

The deciding match takes place in Port Elizabeth on Wednesday.