Skipper Steve Smith says he is leaning towards playing all-rounder Mitchell Marsh as Australia's fifth bowler in Thursday's potentially Ashes-deciding third Test against England in Perth. Smith declined to finalise an Australian XI at his Test-eve media conference Wednesday as selectors mull over the merits of struggling batsman Peter Handscomb and local star Marsh. Handscomb's place is under threat after a total of 62 runs in three innings in the series after a difficult Adelaide second Test in which his batting technique came under the microscope. If recalled, it would be the first appearance for Marsh since a shoulder injury mid-way through Australia's Test series in India earlier this year.