AAP

Under-pressure prop Ben Alexander has been rested as the Wallabies have called for their best scrummager, Sekope Kepu, to combat the abrasive Irish pack on Sunday morning (AEDT).

Kepu will anchor Australia's much-maligned set-piece at Aviva Stadium after coach Ewen McKenzie swung two personnel changes up front for a no-holds-barred Dublin battle.

Fearless flanker Scott Fardy returns to the back-row after recovering from a head knock in the tour-opening 20-13 loss to England, which sees Rob Simmons move back to lock at the expense of Sitaleki Timani.

Powerhouse hooker Tatafu Polota-Nau has also been recalled for his first Test of a injury-riddled year off the bench alongside Waratahs teammate Paddy Ryan.

But the biggest change by far is Alexander being left out; rested on medical advice, according to McKenzie.

The Brumbies tight-head has endured a massive season of both Test and Super Rugby and has enjoyed his share of success as well as pain as the Australian scrum has struggled.

McKenzie admitted Alexander's contributions around the ground had dropped at the end of a long season and team medics felt he'd benefit from a week off.

"He's been carrying soreness and things like that and in the end the medical people advised me that was the best outcome," he said.

Ireland are set to recall a host of Lions big-guns, rested from the 40-9 win over Samoa, including crafty loose-head prop Cian Healy, setting up an important front-row battle with Kepu.

Rated Australia's best technical scrummager, the 125kg Kepu has been waiting for another start since botching his chance in the forgettable 38-12 loss to South Africa in Brisbane, where he blew out of gas.

"He maybe got a bit excited and then burned himself out later in the game then we'd probably hoped so we've worked hard at his conditioning," McKenzie said. "But technically he's very good, very strong at scrum time.

"The game is about balance.

"We want to see that technical expertise show up in the (scrum) but also get a balance in terms of contributions (around the field).

"He's a very powerful player, so it's just a matter of getting the energy at the right moments."

Unlike Alexander, Brumbies teammate Stephen Moore has been backed by McKenzie to finish off the long season strong after playing his "best three" Tests this year in the past month.

Polota-Nau's return, 189cm prop Ryan's call-up and second-rower Timani's demotion gives the Wallabies plenty of power and size on the bench.

McKenzie has kept the same backline which produced seven tries in the 50-20 thumping of Italy in Turin, leaving rookie centres Tevita Kuridrani and Matt Toomua with a big task against Irish pair Brian O'Driscoll and Gordon D'Arcy.

Wallabies: Israel Folau, Adam Ashley-Cooper, Tevita Kuridrani, Matt Toomua, Nick Cummins, Quade Cooper, Will Genia; Ben Mowen (capt), Michael Hooper, Scott Fardy, James Horwill, Rob Simmons, Sekope Kepu, Stephen Moore, James Slipper. Res: Tatafu Polota-Nau, Benn Robinson, Paddy Ryan, Sitaleki Timani, Liam Gill, Nic White, Christian Leali'ifano, Joe Tomane.