Garry Ringrose will make his first senior start at inside centre to solve injury-hit Ireland's midfield dilemma against Australia in Dublin on Saturday.

The 21-year-old has not started a game at 12 since turning out for Leinster's under-20s last season but acquitted himself admirably in the role off the bench against New Zealand last weekend.

Robbie Henshaw's absence through concussion and Johnny Sexton's hamstring problem has forced Ireland into several midfield reshuffles to take on the Wallabies.

Paddy Jackson slots in at fly-half with British and Irish Lions fly-half Sexton sidelined, while Rob Kearney and CJ Stander have overcome concussion issues to start.

Ireland had drafted Ulster centre Stuart Olding into their squad in midweek while releasing midfielder Luke Marshall back to the Belfast province.

But Ireland boss Joe Schmidt has opted to give highly-rated Ringrose his head at inside centre, even though he has not even started a PRO12 match for Leinster in the role.

Ireland boss Schmidt insisted Ringrose's performance under pressure at inside centre last weekend against the All Blacks had won the young gun another chance to impress in the 12 shirt.

"Really it's a reflection of his performance last week," said Schmidt. "I thought Garry stepped in and did incredibly well against New Zealand.

"He slipped a couple of tackles, got one line break and almost got another couple, and he was among our top tacklers.

"So it's another opportunity to invest in Garry.

"He's been in camp with us for a year and a half at different times, and he's been a bit of a long-term investment, that we want to take this opportunity to develop a bit further."

Sexton is replaced by Paddy Jackson (Getty) (2015 Getty Images)

Schmidt conceded Ireland lost some of their attacking stability against New Zealand on Saturday once Henshaw and Sexton went off injured.

But the former Leinster boss remains adamant one more week working together will hand Jackson, Ringrose and Jared Payne the confidence to run a seamless offensive game.

"We lost our shape at points last week, it was quite difficult with those changes," said Schmidt.

"Sometimes you create chances but if you don't have leadership then you don't tend to have cohesion, and guys aren't then in the right place at the right time.

"Robbie Henshaw was an absolutely stand-out player for us in Chicago.

"And not having him for the majority of Saturday's match probably didn't allow us quite so much robustness through the midfield.

Henshaw was concussed against New Zealand last weekend (Jean Catuffe) (2016 Jean Catuffe)

"And not having Johnny (Sexton) didn't quite give us the same kind of organisation.

"Not that Paddy Jackson can't do that, we saw in South Africa in the summer that he can, but he hadn't had nearly as much time in the saddle recently as Johnny.

"So what we're hoping is that they've had a bit of game time together last week, and we've had training since, and hopefully those guys can get a bit of confidence from that.

"And hopefully that confidence can be reflected in the performance we put together on Saturday."

R Kearney (Leinster), A Trimble, J Payne (both Ulster), G Ringrose (Leinster), K Earls (Munster), P Jackson (Ulster), C Murray (Munster), J McGrath (Leinster), R Best (Ulster, capt), T Furlong (Leinster), I Henderson (Ulster), D Toner (Leinster), CJ Stander (Munster), S O'Brien, J Heaslip (both Leinster).