Michael Cheika has revealed that lock Rob Simmons was dropped from the Australia squad to face England in the second Test on Saturday rather than left out due to injury.

Towering lock Simmons was a notable absentee when Cheika named his 23 for the clash in Melbourne, where the Wallabies will be eyeing a victory to draw level at 1-1 in the three-match series.

Simmons suffered a back injury in the 39-28 defeat against Eddie Jones' side last weekend, but Cheika said his decision to pick Sam Carter ahead of the Reds man was not due to a lack of fitness.

"He was available for selection this week," said Australia coach Cheika.

"Any player that's left out is unhappy obviously so that's the challenge for him to improve and get his spot back like all players who are left out of a team.

"That's the nature of rugby, it has been forever. Some guys get picked, some guys don't, and it's how you react accordingly.

"That's what we're looking for from the players who have been brought into the team is here's an opportunity for the players who have remained in the team, here's another opportunity to go and do your best, put your best foot forward.

"You've only got a limited amount of opportunities in the Test jersey so you've got to take every one. Here's a chance for a guy who's been knocking on the door in that role in Sam Carter and going to be his opportunity to be taken."

Cheika opted to name Ben McCalman and Dean Mumm among the replacements for the crunch clash at AAMI Park, with Liam Gill, James Horwill and Wycliff Palu also left out of the squad.