Looks like Harris is in doubt.
Ashes 2013: Ryan Harris in doubt for Perth Test, says report
"Ryan Harris has had an ongoing knee issue throughout his career which we manage after each Test he plays," a CA spokesman said.
"Along with all the bowlers, Ryan is doing a recovery session today and he will bowl tomorrow."
The 34-year-old Harris reported stiffness during the Adelaide Test which finished on Monday.
"I'm a little bit stiff and sore. We have an extra half-day off now," Harris said after Australia clinched victory before lunch on day five of the second Test.
Harris has a tremendous record of 79 wickets at 22.06 in 18 matches.
The Queensland quick's fitness has been a concern for Australia, however, and he's played only six of Australia's 12 Tests in 2013.
Pacemen Doug Bollinger, Nathan Coulter-Nile and James Faulkner, who was 12th man in Adelaide, are possible candidates to replace Harris if he fails to prove his fitness.
The Perth pitch is tipped to be fast and bouncy and suited to Australia's pace attack.
Australia lead the five-match series 2-0 and will reclaim the Ashes with victory in Perth.
http://www.smh.com.au/sport/cricket...or-perth-test-says-report-20131212-2z6vi.html