New Zealand's softballers head into the next phase of their world championship build-up programme with a tour to Canada and the United States over the next month.

The side left Auckland to link up with overseas-based players on Friday.

However, one of those players, and a key element in the world championship planning, pitcher Jeremy Manley will not be joining the side. Work and business commitments have ruled him out and his on-going prospects of being part of the championships could depend on an end of tour meeting he has with coach Eddie Kohlhase.

Manley's absence has resulted in young New Zealand-based pitchers, Nick Hayes of Hutt Valley and Kurt Shollum of Marlborough being added to the side which will meet several top Canadian and American club sides while also playing in the annual Legends and Peligro tournaments.

They will join Heinie Shannon, Penese Iosefa and Tane Richardson in the pitching ranks for the tour.

Manley's absence was regarded by Kohlhase as an opportunity for others to assume the No.1 spot.

The tour is not quite a 'last chance' for players, they will have an internal tour in November before the world championship side is named in December, but it was a great chance to stake claims.

Kohlhase intends to have a good look at players who haven't been under the spotlight, as a result of playing overseas, for the past 12 months while also looking to advance the game being developed for the championships.

New Zealand will be in a rare position in recent times of not being the defending champion, or favourite, when the tournament starts.

They have Australia to get past if they want to regain the title and given the 5-0 thrashing New Zealand suffered at their hands in the last world championships final the job is ahead of them.

The Australian success has been the result of a typically managed Australian Sports Institute programme which saw the Australians win four junior world championships in succession before knocking off the senior title in 2008.

Ironically, much of the pitching development for the Australians has been done by former New Zealand hurlers.

New Zealand pitching lacks dominating figures like the legends of the past in Kevin Herlihy, Michael White or Steve Jackson but steps were in place to develop quality performers who had the ability to dominate like those players at their peak.

Kohlhase said New Zealand's batting was still strong and up with the best in the world but it was the ability to defend that batting that was vital.

"We have to be able to move the ball in game situations. There will be some very good pitching in 2013 from the Canadians, Australians and Japanese and we will need to have a good defensive game," he said.