Sampie Mastriet (below) and teammate Jamba Ulengo in a gym session ahead of the Sevens competition in Wellington. Picture: Marty Melville/Getty Images

Wellington – The imposing South Africans with their rock-solid defence are being targeted as the team to beat when the New Zealand round of the IRB world Sevens series gets underway in Wellington on Friday.

South Africa, coming off back-to-back titles in Las Vegas and Port Elizabeth, lead the series by one point over perennial tournament pacemakers New Zealand, going into the fifth of nine rounds.

While New Zealand have traditionally reigned with a mix of guile and speed, South Africa have brought a new element to rugby's short-form game this year, which will make its debut at the Olympics in 2016.

“The physicality that the South Africans bring, they're not top of the series for no reason. They pride themselves on defence, they're very, very good in that area,” said Simon Amor, coach of the Wellington defending champions England.

When they won in Las Vegas two weeks ago, South Africa conceded only 14 points in the whole tournament.

They came in two games when beating Kenya 19-7 in pool play and downing New Zealand 14-7 in the final.

“This tournament will be won by defence and we will keep working hard on that and pushing that culture to make sure we stay solid enough to hopefully win another title,” South African captain Kyle Brown said.

New Zealand, desperate to reassert themselves after losing the Las Vegas and Port Elizabeth's finals to South Africa, will unveil another young find to a side that has won the world series 10 times.

Coach Gordon Tietjens described 18-year-old Akira Ioane as an exciting talent.

“And when the opposition don't know a lot about a certain player it's probable a good opportunity will come his way,” Tietjens said.

Ioane has “a huge amount of potential, very quick, very big and ... he's a very, very good footballer as well”.

South Africa have been drawn in Pool A with England, Wales and Portugal, while New Zealand are in Pool B with Fiji, France and Spain.

Scotland, Argentina, the United States and Canada make up Pool C with Samoa, Australia, Kenya and Tonga in Pool D. – Sapa-AFP