Four months after being berated by coach Steve Hansen for his lack of fitness, the big Auckland loose forward will start a test against South Africa.

Luatua replaces the injured Liam Messam at blindside for Saturday’s Rugby Championship match at Westpac Stadium in one of three changes to the team that started against Argentina in Napier.

A fit-again Aaron Cruden returns as expected in place of Beauden Barrett at first five-eighth, while lock Jeremy Thrush comes in for Sam Whitelock, who is out with a rib injury.

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There had been some interest in pairing Richie McCaw and Sam Cane on the flanks, but Luatua fits with Hansen’s oft-stated line of doing what’s best for the team.

The straight swap at blindside causes minimal disruption to the balance of the squad, with Blues teammate Patrick Tuipulotu coming into the reserves to cover the second row after recovering from an ankle injury.

Luatua also adds important size in the lineout against always disruptive Springbok veteran Victor Matfield, but Hansen will be looking for far more from a player of immense potential.

The 23-year-old Aucklander burst onto the scene with such force last year it seemed the All Blacks had uncovered an instant hit.

Physical, full of energy and athletic in open spaces, Luatua tore through 2013, playing 11 tests, starting in five of them and looking throughly at home. And then he fell off the wagon, inconsistent and overweight during the Blues’ Super Rugby campaign.

The situation was bad enough for Hansen to make an example of his young forward during a training camp in Christchurch in May, putting him through an exhaustive fitness session and then publicly airing his concerns.

Luatua was omitted from the All Blacks squad for three tests against England in June, replaced by Victor Vito, and left to contemplate his situation.

He responded enough to get a recall for the Rugby Championship and struck an energetic figure when he dived over for a late try during an 18-minute cameo late in the 51-20 thrashing of the Wallabies at Eden Park.

Luatua’s chance has come via injury, with Jerome Kaino (elbow) and Messam (thigh) joining Vito (neck) on the physio’s table.

He still has some convincing to do, and will not want any moments similar to the embarrassing clearance kick that blew up in his face when he was playing for Auckland against Tasman two weeks ago in the national provincial competition.

Thrush’s selection has similarly come via injury though he looked anything but a second choice against the Pumas and is fully deserving of his seventh test cap but just third start.

Tuipulotu is a raw prospect in the reserves, having just two previous caps and very little game time, as he has struggled with injury.

The All Blacks bench also holds some intrigue, with wing Cory Jane replacing Malakai Fekitoa, who was the only reserve not used during last weekend’s 28-9 win over the Pumas.

That potentially leaves the midfield vulnerable should veterans Ma’a Nonu or Conrad Smith come off injured. Wing Ben Smith provides adequate cover for centre but has little experience at second five-eighth.

Smith remains on the wing, with Israel Dagg’s efforts in his home town of Napier earning him another start at fullback, where his kicking game may again be a vital asset against the Springboks.

All Blacks: 15 Israel Dagg, 14 Ben Smith, 13 Conrad Smith, 12 Ma’a Nonu, 11 Julian Savea, 10 Aaron Cruden, 9 Aaron Smith, 8 Kieran Read, 7 Richie McCaw (Captain), 6 Steven Luatua, 5 Jeremy Thrush, 4 Brodie Retallick, 3 Owen Franks, 2 Dane Coles, 1 Wyatt Crockett
Replacements: 16 Keven Mealamu, 17 Joe Moody, 18 Ben Franks, 19 Patrick Tuipulotu, 20 Sam Cane, 21 TJ Perenara, 22 Beauden Barrett, 23 Cory Jane.