Before the Wallabies game against Argentina in Perth, Folau made the candid admission 2016 had been the most challenging year of his rugby career to date.

Folau has scored three tries in 16 appearances in 2015 and 2016, but Larkham backed the Wallabies fullback to hit his straps when Australia takes on South Africa in Pretoria on Saturday (Sunday AEST).

"He's been more motivated than ever I think to get out there and play well," Larkham said. "The ball's not necessarily going to him in the right spaces at the right times, but he's very enthusiastic about improving and adding to this team and we certainly have seen that at training over the last month.

"Mainly attack is the area he's shown the most enthusiasm in the last month of training. He's been exceptional. I've only worked with Izzy now for 18 months, if that, and he's a different person now than he was 18 months ago, definitely.

"We went through a pretty tough stretch with the games we lost, but there's a lot of motivation in the group at the moment to become better and I don't think anyone's driving that more than Izzy at the moment."

So much has been made of where Folau is best suited, be it at fullback, wing or in the midfield.

Regardless of the number on his back, Larkham said it was his job as attack coach to ensure Folau was getting plenty of ball.

"Our challenge as coaches is to make sure that we get him opportunities in a bit of space," Larkham said. "Like everyone, you get a little bit frustrated when you drop the ball or the ball doesn't come to you and you're in a bit of space, but I don't think Izzy's shown that more than any other player. He's been really enthusiastic at training, he's accelerating through gaps, his communication has certainly gone to a new level now."

Coach Michael Cheika confirmed his bench at the captain's run on Friday, with Melbourne Rebels speedster Sefa Naivalu set to become Wallabies No. 900. Lopeti Timani drops out of the match day 23.

"I think a few people have been waiting to see Sefa at this level for a while," Larkham said. "He's been exceptional at Super Rugby level. If you have a look at about every involvement he's had in Super Rugby where he's had his hands on the ball, he's making some sort of a line break.

"That's the biggest factor he's going to bring to this team. The excitement when he comes off the bench and gets his hands on the ball, it will be very exciting for the fans."

Captain Stephen Moore reached a milestone of his own on Friday; he finally got to pick the song at Australia's captain's run – a tune by the Australian band Cog - after putting in requests for two years.

While the speaker that played the song was a "letdown", Moore gave his assurances the Wallabies would be of better quality when they make the trip to Pretoria aiming to break a five-year drought on South African soil.

"Today [Friday] I guess is just more about mental preparation and making sure that we're ready to go in that space," Moore said. "I know it seems relaxed here but we're well aware when we get out there at Loftus, it's going to be a real ding-dong battle and we're expecting them to come out and play well."