Wallabies coach Ewen McKenzie says he can’t keep throwing giant youngster Will Skelton into the Test fray, insisting Australia’s biggest rugby asset has to be nurtured carefully.

Skelton, 22, has been dropped from the match-day 23 for Saturday’s clash against the physical and abrasive Springboks in Perth, with McKenzie instead opting for former Test captain James Horwill on the bench.

“Will Skelton, until Kyle Godwin turned up, was the youngest in the team,” McKenzie said.

“So I think we’ve got to acknowledge that we can’t expect Will Skelton to be the one out there winning every game for us.

“He’s got some extraordinary skills but we need to nurture him.”

McKenzie said Skelton would find his development more beneficial by getting a mix of Test rugby off the bench, and full 80 minute performances in the National Rugby Championship (NRC).

“We need to develop him in a broad sense, not just throwing him out there against the best players,” he said.

“He’s got great potential and should have a long career – we just need to manage that.”

Another reason McKenzie has opted to recall Horwill is to provide a back-up lineout caller for Rob Simmons, who hasn’t been substituted once in the past four Tests – including their last start 51-20 thumping from the All Blacks.

And with Australia down to their fourth string hooker in James Hanson, it’s expected that master aerial ball thief Victor Matfield will heap the pressure on the Wallabies at the lineout.

“Horwill’s been contributing very well and everyone knows he’s been our second lineout caller,” McKenzie said.

“That allows us to look at the second half of the game in particular in terms of how we replace players.

“You can’t just be expecting some guys to play all the time and maintain form.

“We need to be able to share some of that load – so it gives us options.”