Injury clouds over Shane Watson and Ryan Harris threaten to deny Australia the rare opportunity of completing an Ashes clean sweep over England with the same line-up for five straight Tests.
Australia moved four-nil up in the series with a commanding eight-wicket win at the Melbourne Cricket Ground, but Watson's groin strain and Harris's knee and foot complaints have left selectors pondering possible changes to the bowling attack for the fifth and final Test starting in Sydney on Friday.
Allrounder James Faulkner could be poised for a recall if Watson is ruled out, while left-arm paceman Doug Bollinger and uncapped Nathan Coulter-Nile are also be in the frame if Harris is rested.
Harris has fought an ongoing battle with knee soreness and the 34-year-old has also suffered from foot blisters in Melbourne.
Number three batting all-rounder Watson is averaging 41.85 in the series, but coach Darren Lehmann says he wants five bowlers in the side to share the load.