Fourth ODI scores
New Zealand beat South Africa by seven wickets
South Africa 279-8 (De Villiers 72, Du Plessis 67, Amla 40; Patel 2-57)
New Zealand 280-3 (Guptill 180*, Taylor 66; Tahir 2-56)
Report
Martin Guptill marked his return from injury with a phenomenal 180 not out to steer New Zealand to a series-levelling seven-wicket win over South Africa in the fourth ODI in Hamilton.
Opening batsman Guptill was restored to the team after recovering from hamstring issues and responded by blasting 15 fours and 11 sixes in an innings that helped the Black Caps reach a victory target of 280 with five overs to spare.
Proteas captain AB de Villiers' unbeaten 72 from 59 deliveries, plus a more passive 67 from Faf du Plessis, helped the tourists reach 279 for eight but that total was never going to be enough once Guptill got into his stride.
The series now stands level at 2-2, with a mouth-watering decider to come in Auckland on Saturday.
Having won the toss and batted first, South Africa lost Quinton de Kock to a first-ball duck but after Hashim Amla (40) and then Du Plessis staged a recovery, they slipped from 128 for two to 158 for six at the end of the 37th over.
De Villiers had made only 27 from 37 deliveries, with one four, but upped the ante as South Africa's innings approached its climax, cracking three more fours and three maximums, while lower order cameos from Chris Morris and Wayne Parnell swelled the total further.
South Africa made an early inroad by soon dismissing Dean Brownlie but Guptill, replacing Tom Latham in the team, settled into his stride with a maximum off Parnell in the next over.
Boundaries seemed easier to come by for Guptill, who brought up his fifty shortly before Black Caps captain Kane Williamson was trapped lbw by Imran Tahir to end a 72-run partnership.
New man Ross Taylor was far more circumspect at the crease but was allowed to settle in as Guptill kept motoring along, bringing up three figures and a 12th ODI ton from only 82 deliveries.
Guptill has a reputation for going big once set, having amassed an unbeaten 237 - the second-highest individual ODI score - against West Indies in the 2015 World Cup quarter-final, and he continued to find the boundary regularly.
Taylor was on 40 from 81 balls but cut loose with a six off Dwaine Pretorius to bring up his half-century and soothe any fears the hosts would slip up in pursuit of their total.
Guptill surpassed 150 in the next over and although Taylor departed for 66, chipping Tahir to mid-on to end a 180-run stand, Guptill thrashed the leg-spinner for back-to-back sixes and fittingly brought up victory for New Zealand immediately afterwards.