All Black trio Isaia Toeava, Israel Dagg and Richard Kahui will travel to South Africa to put their case for selection in the World Cup squad.

There is some stiff competition for places in the New Zealand backline, and the trio have all recovered from long term injuries in time to stake their claim on a place in the squad.

Toeava and Dagg made their comebacks in the NPC last weekend for Auckland and Hawke's Bay respectively, while Kahui is expected to feature for Waikato against Canterbury next week.

All Blacks coach Graham Henry is prepared to give all three players an opportunity to prove their worth.

"We have to name it (the World Cup squad) the Tuesday before the Australian test (which is played in Brisbane on August 27), so it's pretty important that they play," Henry told NZPA.

Toeava and Dagg are likely to be battling Cory Jane, Sitiveni Sivivatu, Hosea Gear and Zac Guildford for the outside back berths, as Mils Muliaina is a virtual certainty.

In the midfield Kahui is unlikely to replace Ma'a Nonu, Conrad Smith or Sonny Bill Williams, so his selection could depend on how many centres Henry chooses to take with him.

henry explained that the good form shown by so many backline players was adding to his selection headache.

"I was clear a couple of weeks ago, now I'm pretty foggy about that," he said.

"Everybody who's been given the opportunity has played well, so after next week's Test in South Africa we've got to make a decision.

"You're going to have guys playing in that game who haven't played a lot of footy lately against their top team, and that's going to be a great challenge."

Loosehead prop Tony Woodcock could also make the tri-Nations trip to South Africa despite struggling from a minor hamstring injury.

"He's played 80 tests, so he knows what he's doing," Henry said. "He won't play the whole game, but we just need to get him back in the fold."

However, wing Sivivatu  won't be travelling after sustaining a bad eye injury while scoring a try against Australia.

"He's got a fractured eye socket, which is not good," Henry said.

"He probably will miss South Africa but probably will be right for Brisbane."

The squad for the South African trip, likely to be kept to 24 players instead of the allowed 26.