We're just not up to it - NZ coach
New Zealand's coach Mike Hesson said it was understandable his side were left reeling at 47 for six at stumps on day two of the second test against South Africa in Port Elizabeth on Saturday.
"South Africa is a tough place to tour, notwithstanding they're the No 1 test side in the world," Hesson said after his side still trailed their hosts by 478 with only four wickets remaining.
"We're ranked No 8 for good reason but our players are working extremely hard to get better."
South Africa declared on 525 for eight shortly after tea and then pummelled the New Zealand batsmen with an onslaught of extremely hostile bowling for the last session before stumps.
Opening batsman Martin Guptill (1) and Kane Williamson (4) both fell to Dale Steyn while Morne Morkel kept up the pressure from the other end.
There was no respite for the Kiwis when Rory Kleinveldt and left-arm spinner Robin Peterson came into the attack.
Kleinveldt took two quick wickets, which included that of century-maker in Cape Town Dean Brownlie (10) and Daniel Flynn who went for a duck.
Not to be outdone, Peterson enjoyed a double-wicket maiden and stumps could not come soon enough for the Black Caps.
"We all have to share the responsibility for the poor performance but you can't fault the players' work ethic," Hesson said.
"The support staff are putting in the work behind the scenes and the players are training and working hard in the nets but we're just not up to it.
"After Cape Town, we could have just put our feet up and given up but we didn't and people back home need to realise that we're trying our very best but we're completely outclassed."
Faf du Plessis and Dean Elgar, who piled on the runs after lunch, both scored centuries in their fourth and third tests, respectively.
Du Plessis took 202 balls, including 12 fours and two sixes, for his second test century, while Elgar reached the milestone in 170 balls.
Their 131-run partnership was South Africa's highest sixth-wicket stand against New Zealand and also the highest by the Proteas at Axxess St George's.
"It's a nice feeling to get my first home test century," Du Plessis said after making a century on debut in Adelaide in November 2012.
"In Australia, I was playing for the team and to save the test, whereas today it was all about my own performance so it was nice to go through it.
"I'm aware that I'm in good form at the moment and need to make the most of it because I know it won't always be like this in test cricket."
Du Plessis empathised with the New Zealanders and said it was very difficult batting out there for most of the day.
"The ball was swinging around a lot but we have the advantage of extra pace in our attack," he said.
"Our bowlers are able to control the line and length a lot more and someone like Dale Steyn is very hard to face when he's bowling well." Elgar, who made a pair in his first test, and 21 in his only other innings – in the Cape Town test last week – played with more determination, stroking some magnificent boundaries.
However, runs dried up after Du Plessis departed for 137, but captain Graeme Smith magnanimously delayed his declaration until after tea to allow Elgar his maiden hundred.
"I got the message to try and get my 100 before tea but when I walked into the change room (on 91 at tea) Graeme said I had time to get it after tea and I'm really grateful to him for that," said Elgar.
"I know I have to be more consistent to make it difficult to be left out of the side but I'm still young and still in awe of the big-name players in our change room."