The return of several key players from injury has bolstered the New Zealand squad for their Tri-Nations campaign.

The team will be boosted against Australia and South Africa.

Captain Richie McCaw (knee), Rodney So'oialo (neck) and Sitiveni Sivivatu (shoulder) will, as expected, all be involved for the first time this year after recovering from the injuries which kept them out of the drawn series with France and win against Italy.

Also recalled are wing Hosea Gear and forward Jason Eaton, who were both part of last year's end of season grand slam tour and the recent successful Junior All Blacks' Pacific Nations Cup campaign.

Eaton comes in for the injured Ali Williams, who will undergo surgery on Monday on his right Achilles and left shoulder. The 61-Test lock is out of rugby for the remainder of the year.

Gear replaces Lelia Masaga, who was a late call-up for the injured Rudi Wulf in the June Tests.

After three scratchy performances All Blacks coach Graham Henry admitted the team was under no illusions how challenging this year's Tri-Nations would be.

"It's going to be a huge contest right from the first Test. But this group of players has the resolve and the character to meet that challenge head on so we are expecting it to be another massive competition between the three top-ranked countries in world rugby," he said.

Liam Messam is the biggest casualty from those who were involved against France and Italy, with Masaga and another replacement player, George Whitelock, who scored against Italy on his debut, also not included.

The All Blacks open the defence of their title against Australia in Auckland on July 18 before they head to South Africa for two Tests against the Springboks.

Players not considered for selection due to injury include lock Williams (Achilles), wing Wulf (shoulder), flanker Adam Thomson (hand), centre Richard Kahui (shoulder), lock Anthony Boric (toe), halfback Andy Ellis (ribs), hooker Corey Flynn (forearm), flanker Scott Waldrom (back) and fly-half Daniel Carter (Achilles).

The injury news continues with utility back Isaia Toeava likely to miss the opening three Tests with a stress fracture in his left foot.

Fly-half Stephen Donald is also recovering from a hamstring strain.

The All Blacks squad will assemble in Wellington for a two-day camp on Wednesday and Thursday next week and four players will assemble with the squad for the camp as cover.

These are Hurricanes and Wellington utility back Tamati Ellison, Crusaders and Canterbury fly-half Stephen Brett and 2008 All Blacks Ben Franks and Anthony Tuitavake, who were all members of the victorious Junior All Blacks squad.

New Zealand squad:

Backs: Jimmy Cowan (Southland), Stephen Donald (Waikato), Hosea Gear (Wellington), Cory Jane (Wellington), Brendon Leonard (Waikato), Luke McAlister (North Harbour), Mils Muliaina (Waikato), Ma'a Nonu (Wellington), Joe Rokocoko (Blues), Sitiveni Sivivatu (Waikato), Conrad Smith (Wellington), Isaia Toeava (Auckland), Piri Weepu (Wellington).

Forwards: John Afoa (Auckland), Wyatt Crockett (Canterbury), Aled de Malmanche (Waikato), Jason Eaton (Taranaki), Bryn Evans (Hawke's Bay), Owen Franks (Canterbury), Andrew Hore (Taranaki), Jerome Kaino (Auckland), Tanerau Latimer (Bay of Plenty), Richie McCaw (Canterbury, captain), Keven Mealamu (Auckland), Kieran Read (Canterbury) Isaac Ross (Canterbury), Rodney So'oialo (Wellington), Brad Thorn (Canterbury), Neemia Tialata (Wellington), Tony Woodcock (North Harbour).