Sir Steve Hansen believes All Blacks have 'big advantage' over 'vulnerable' Springboks

Rassie Erasmus' side haven't played since securing a narrow victory over Los Pumas in Argentina a fortnight ago, a match that saw several players return from injury, including the likes of Siya Kolisi, Lood de Jager, Eben Etzebeth and Sacha Feinberg-Mngomezulu.

Meanwhile, Dave Rennie's side has played three of the United Rugby Championship clubs and have been able to test combinations and become accustomed to the demands of playing in South Africa.

Those games have given New Zealand a massive advantage heading into Rugby's Greatest Rivalry series opener against the Springboks at Ellis Park, according to the 2015 Rugby World Cup-winning head coach.

"The big advantage of touring like this is you get to give your players the opportunity to play against opposition that you know you're going to beat, let's be honest," Hansen explained on the Rugby Unity podcast.

"So what are you practicing? You're practicing the things you want to be able to do to a really high level at test level, but you're practicing against opposition that wants to rip your head off, and that's what we've seen.

"That's what they're going to get on Saturday. The South Africans are going to come out and want to be really, really physical, slow the game down, and then they'll try to speed it up when they bring on their reserves, with the big forwards coming on and then say, 'Okay, let's go to another gear.'

"So the All Blacks have experienced all that. They've had the opportunity to practice. Their combos have been pretty good, and I think they've been quite smart in how they've selected the teams. You can see they're selecting combinations rather than a straight-out Test team."

Hansen feels that the Springboks could be lacking match fitness heading into the first Test match, considering how many players have just come back from injury. While he believes this plays into the All Blacks' favour, he is wary of making the visiting team the favourites for the clash in Johannesburg.

"South Africa will be at their most vulnerable in this game because they haven't played together for a while, because of injuries, with no game time available to them other than the Argentinian Test, where they didn't take a lot of their top liners," he said.

"You would imagine it's an advantage to New Zealand because of that, but then you take into account that it's home and you're playing the number one team in the world. So it's going to be a good encounter. Exciting. Looking forward to it."

The All Blacks have had injuries of their own with Rennie stating after the victory over the Bulls that the coaching staff wasn't overly confident that Damian McKenzie would be fit to face the Springboks.

They have also called up scrum-half Noah Hotham with Cortez Ratima nursing an injury, while hooker Codie Taylor only made his first appearance on the tour at Loftus.

If McKenzie is available this weekend, Hansen says that Beauden Barrett is a "ready" replacement and could line up in the number 15 jersey after his performance versus the Bulls.

"Well, we saw people like Codie Taylor get on the field and get some game time, and he came through it really well," he said as he ran through the standout performers in Pretoria.

"His experience made a big difference to their scrum penalties. I really like Kyle Preston; he clears the ball really well. So, I think he's going to be pushing for a spot.

"Dave Rennie said that both Will Jordan and Cam Roigard will be available, but they're sweating a little bit on McKenzie. So, I think they've got a ready replacement with Barrett; whether he starts or comes off the bench, he can cover those two roles the same as McKenzie does.

"You've got Leroy Carter, who played outstandingly, I thought. Josh Moorby is all over the place; he can play full-back and play centre, he can play wing, and he gets the ball; he is an excitement machine, isn't he? Like he just creates space for himself and others. So there's plenty to be able to pick from.

"Tyrel Lomax getting game time was important for him. He's a guy who needs to play on a regular basis to be at his best - getting him out there was good. Locks, I don't know who they're going to take. Whether they play Tupou Vaa'i at six and take a combination of Josh Lord, Sam Darry, and Vaa'i, or Fabian Holland.

"I'd say Holland will definitely be one of them. So the other two slots, they've got three or four really good candidates. I don't think they're going to be short on people to pick and form."

READ MORE: Rassie Erasmus weighs injuries, selection and All Blacks rivalry