Melbourne - Sidelined Australian opener Simon Katich says his Achilles injury is recovering quicker than expected, putting him on track for a possible surprise comeback in the final Ashes Test.Katich, 35, said he was "really happy" at how the partial tear was reacting to rehab and physio after he hobbled through the second Test in Adelaide and was ruled out for the rest of the series."It's hard to say when I will come back but it's tracking quicker than we thought it would at this stage," Katich said, according to AAP news agency on Wednesday."But I can't give any definites until I start running and see how it pulls up after that, and that may be in the not too distant future."So I don't know if I'll be ready in time for the Sydney Test. And then it's a decision for the selectors and the ball's out of my court in that respect."Katich was replaced by New South Wales' Phillip Hughes, who scored only two and 12 in last week's Perth Test. The fifth and final game in Sydney starts on January 3.