South Africa were thrown off guard by a 59th-over ball change in Hamilton, according to Morne Morkel. New Zealand were building steadily in the middle session, on 163 for 1 when umpires Bruce Oxenford and Rod Tucker ordered a ball change, having felt the ball had gone out of shape. South Africa had been getting some reverse and were clearly unhappy with the change, and the replacement - with the changed ball they conceded 80 runs in the next 21 overs, as Kane Williamson took control.

"It was at a crucial stage. We had just got the ball to reverse. From a mental point of view, it cost us about 15 overs to get back into the game," Morkel said. "For me, it's a grey area because when they change the ball, they pick a ball for you. For me that doesn't add up. I would rather they give the fielding team three balls to pick from. But then I am also blaming my tools and I can't do that."

Instead, Morkel gave full credit to Williamson, who transferred pressure back onto South Africa and marshalled Jeet Raval to a career-best 88. "Kane plays length very well. Anything with slight width, he will cut and play square. Then if you go that touch fuller, especially on this sort of surface, it's easy. The margins are very small to him," Morkel said. "The short ball is always key, but here with the surface on the slower side, it's not such a big threat, so guys can just wait for that fullish delivery. He can bat time and that's the sort of thing that bowlers don't like."

Before the series began, South Africa had identified Williamson's importance and they have duly been on the receiving end of two centuries in this series. Raval indicated his captain still has more to offer. "He is one of the best players we've got, if not the best," Raval said. "The way he goes about his business is awesome. He is never satisfied with 100, or 150, he wants to get big runs and help the team. I was lucky that I was batting at the other end and got to pick his brain a little bit."

Jeet Raval is a picture of concentration Getty Images

Raval shared a record second-wicket stand with Williamson against South Africa, of 190, but could not add a personal milestone of his own. After five fifties, he has yet to convert to a ton and said his attempt this time was the most difficult. "It's a world-class bowling attack. You are made to work hard for every single run. It wasn't easy out there. I felt like a clown batting with the master at the other end," Raval said. "That's what Test cricket is about - it's challenging and it never gets easier. Every time you score a run - it's bloody hard work. You have to deny them for as long as possible, and then hopefully they come to you and you score runs."

Although Raval had the best mentor he could have asked for urging him on, a second-new ball proved too much for the opener. Yet he remained proud of his efforts. "You go through periods where you are doubting yourself or second-guessing yourself. Kane came down and said 'stick to your game plans and your routines'. That just calms you down. He could see a couple of times when I was getting ahead of myself," Raval said. "To watch him bat at the other end was unbelievable and to get the partnership with him was outstanding."

Once South Africa broke that stand, they took two more quick wickets but, with Williamson still there, they would consider themselves to be on the back foot, irrespective of what ball they hold. "There's only one team under pressure now and that's us," Morkel said. "We need to come with the right attitude tomorrow. We know they are going to come really hard at us in the second innings to get the win. It's a nice way for us mentally, we speak about being mentally strong. It would be a great way for us to finish the season if we can hang on."