All Blacks rugby coach Graham Henry has made the first voluntary change to his first-choice line-up this season in a bid to counter South Africa's powerful scrum.

Prop Greg Somerville was promoted ahead of regular tighthead Carl Hayman, almost certainly to counter the scrummaging style and power of veteran Springboks giant Os du Randt in Saturday's Tri-Nations test at Jade Stadium.

Apart from the clash with Argentina last month when several second-choice players were given a run, the only time New Zealand's selectors have previously strayed from the 15 who started the first test against England has been due to injury.

Henry said it was a tough decision to leave Hayman out, also breaking up the tight five that dominated Australia in last Saturday's 16-7 win at Wellington.

"It was discussed in depth and the decision was made. I guess that's the job of the selectors, to try and make correct decisions for particular games," said Henry, who didn't want to discuss the technicalities of the change.

However, he didn't shirk from expressing his respect for South Africa's excellent forward performances that have given them - like the All Blacks - an unbeaten record this year.

"The scrum is obviously one part of their game that's improved. It's traditionally very strong and they appear to have scrummed very well in their four games this season," Henry said.

"The lineout's always been pretty potent and they are driving the ball well.

"They seem to be very highly motivated, I'm not saying they weren't highly motivated last year, but they seem to be on the job."

Du Randt, weighing 127kg, has returned from a long-term knee injury to play in every test this year. The man who was the rock of their 1995 World Cup triumph had retired after playing in the 1999 third/fourth World Cup playoff defeat of the All Blacks.

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