The Irish took the series to a decider with a 26-21 win in Melbourne after their full-strength team returned after being rested in game one.

Genia suffered a broken arm that requires surgery on Sunday after he was allegedly "king-hit" off the ball by Irish prop Ciran Healy in the 25th minute.

"We ran the play round the front and Will is the decoy around the back and he got king-hit from the side, it looked like a shoulder, and when you're not expecting it that's what happened," Australia coach Michael Cheika said.

Genia is expected to be sidelined until at least the Rugby Championship starting in August.

Coleman went down in friendly fire with his head connecting with that of teammate Israel Folau in the second minute of the second half and suffered a suspected fractured cheekbone.

Cheika said the lock would go for scans on Sunday but he had a "very nice golfball on the side of his head".

The Australians haven't put the Genia incident forward to be cited but that doesn't mean it won't be picked up by the independent citing commissioner Kiwi Michael O'Leary, who has 48 hours to do so.

Despite the small winning margin, Ireland dominated most facets of the game as they starved the home side of ball.

Cheika said his team needed to improve their discipline after giving away 15 penalties and their kicking game, which was so effective in Brisbane in the opening Test.

Ireland also did very well to isolate Folau, who was a match-winner in game one.

"I don't know if we played good enough to go two nil up," Cheika said.

"I know we scored three tries to two but I just think we need to trust our systems a bit better.

"We gave away some 50:50s and we shouldn't have that doubt and that will be a work-on for next week.

"We need to do what we do and the rest will turn out right because when we do do it, on defence or on attack, it's pretty good."

- Australian Associated Press