The Kangaroos are facing a front-row crisis at the Rugby League World Cup after David Klemmer and Aaron Woods were put on report during their 34-0 walkover of Lebanon.
Klemmer was penalised for knocking out Cedars second-rower Chris Saab midway through the first half on Saturday, with his shoulder making contact with Saab's head.
Woods also faces a nervous wait after getting booked for a dangerous lifting tackle on Tim Mannah in the second half of their final pool game.
Their status for a likely final-eight clash against Samoa in Darwin won't be the only concern for coach Mal Meninga, whose side needed another big second half to overcome their slow start.
Cameron Munster recorded another double in just his second Test, while James Maloney, Boyd Cordner, Dane Gagai and Tom Trbojevic also got on the scoresheet.
After committing three turnovers inside the opening 25 minutes at Allianz Stadium, Maloney finished his first outing of the tournament with a try and two try assists.
Lebanon will face Tonga in their quarter-final should England beat France on Sunday.
However coach Brad Fittler may have problems of his own with Michael Lichaa (cramps) and Mitchell Moses (shoulder) joining Saab in failing to finish the match.
Spurred on by most of a raucous 21,127 crowd behind them, a determined Cedars outfit held the defending champions to a 10-0 lead at halftime.
Munster began the scoring with an easy try in the eighth minute, but that failed to deter an energetic Lebanon defence that pressured Australia into eight first-half errors.
Arguably the biggest cheer of the night was when Abbas Miski denied doppelganger Josh Mansour a certain try with a one-on-one strip in the 21st minute.
But it didn't take long for Australia to double their advantage on Maloney's try, set up by an offload from his future Penrith teammate Reagan Campbell-Gillard.
Back-to-back penalties put Lebanon on the back foot early in the second half, and Munster made them pay by slicing through for a soft try off the restart.
Cordner finished off a Maloney grubber in the 55th minute, before Gagai and Trbojevic completed the rout with tries in the final five minutes.
Skipper Cameron Smith also got his first major rest of the tournament after being substituted for utility Ben Hunt at halftime.