The Black Ferns are heading to England quietly confident of their chances of winning a fourth successive women's rugby World Cup title despite going in cold.

New Zealand face South Africa in their opening match at Surrey Sports Park in Guildford next Saturday and it will be their first international outing since they split a two-test series with England last November.

The lack of a national provincial championship this year means the only competitive rugby those in the 26-strong squad have had is for their clubs.

Skipper Melissa Ruscoe said she and her teammates, who flew out of Auckland last night, were well aware of the big step up from club to test level. "In some ways, you could say we're underdone," the Canterbury flanker said.

"We've not had the preparation we would have liked, but we've pretty much done what we can with what we've got."

That compares with the build-up for most of the other 12 competing countries, who have had friendly matches and, in the case of England, France, Wales, Scotland and Ireland, the annual Six Nations event.

But Ruscoe was upbeat about the Black Ferns' chances of defending their crown.

"We're confident," she said.

Ruscoe, who was part of the last campaign, is one of 11 players with World Cup experience.

Two of them, first five-eighths Anna Richards and lock Monalisa Codling, both from Auckland, will be attending their fourth World Cup, having played in each of New Zealand's title victories in 1998, 2002 and 2006.

Richards, 45, whose 44 tests make her New Zealand rugby's most capped female player, was called up after Cantabrian Amiria Rule was forced out with injury.

The tournament format involves three pools of four teams, with the Black Ferns' other preliminary opponents being Australia and Wales. The three pool winners and the best second-placed team qualify for the semifinals, with the final scheduled for September 2 at The Stoop, home of Harlequins club.

Ruscoe said England, beaten finalists the past two times and winners of four successive Six Nations titles, would have to be rated as favourites.

She said reports from Britain suggested the English were feeling pretty confident, "and so they should be".

"It's their home ground, they have had a fantastic build-up, they have money, they have professional players. They are ... favourites, but I like the underdog tag and I think we can use that to our advantage."