Rugby World Cup 2019: Steve Hansen backs Richie Mo'unga to perform against Springboks

All Blacks coach Steve Hansen is backing first-five Richie Mo'unga to shine what will be the biggest test of his young career against the Springboks on Saturday night. 

The 25-year-old has been given the reins in the 10 jersey for New Zealand's opening Rugby World Cup match against South Africa, with Beauden Barrett shifted to fullback.

Mo'unga, who has played just 12 tests, has won three Super Rugby finals - but is a relative newcomer on the international scene, with seven of his games in the black jersey coming off the bench. 

Despite being a relative novice at test level, Hansen has faith that the Crusaders pivot can deliver on the big stage. 

"We wouldn't be picking him if we didn't think he was ready," said Hansen.

 "What are his attributes? He plays some scintillating rugby at times, he's very good with the ball in hand, he's got pace, a great kicking game, good vision.

"He's got all the attributes to be a wonderful player.

"He's just got to go and do that on the highest stage, and he's got the mental fortitude to want to jump out and announce himself come Saturday. 

"He follows in the footsteps of some greats, playing with one of the current ones who's gone back to fullback."

The atmosphere is expected to be intense with Yokohama Stadium set to be at full capacity, as all 72,327 tickets have been sold. 

Hansen expects there to be plenty of nerves - but insists that's a good thing.

"We've had a really good week. Preparations have been great. The boys are excited about it.

"I think we're in good shape from a match fitness point of view. Will there be nerves? Of course. If there aren't, we're in trouble. Nerves are a good thing, but once the game begins I think we'll switch on and get on with it.

The All Blacks are looking to win the World Cup for the third consecutive time, but he expects it to a tough challenge this time around. 

"It's going to be competitive - they're always competitive. It always makes me chuckle when I hear people say this side can't win, or this team is going to win.

"There are a number of sides who are capable of winning it because they have the talent in the group, but with that comes higher expectation, and with higher expectation comes more pressure. And if you don't cope with the pressure, it will overwhelm you. 

"There are probably more teams who can win this tournament than the last one. In 2015, there were probably two or three; this time, probably five or six, which is great for rugby."

Meanwhile, midfielder Jack Goodhue says he'll be fit for the All Blacks' next match against Canada on October 2 as he continues to battle a hamstring injury. 

"I'm running well, I'm pretty happy with it. I'm feeling good, the body's feeling good otherwise. I think I'll be available for the next game." 

Essential Guide to 2019 Rugby World Cup

Everything you need to know about rugby and the World Cup...

The ninth Rugby World Cup kicks off on September 20 in Japan - the first time it has been hosted in Asia.

Join us at 9:45pm Saturday for live updates of the All Blacks v South Africa World Cup clash.