Australia is grappling with huge changes after ex-skipper Michael Clarke, Brad Haddin, Ryan Harris, Chris Rogers and Shane Watson all retired during the Ashes test tour.
The new-look Australian squad arrives in Dhaka on September 28 including two uncapped players in 30-year-old paceman Andrew Fekete and 22-year-old batsman Cameron Bancroft.
Rahim said test minnows Bangladesh would have been competitive even if Australia had been packed with formidable veterans, but their chances of snatching victory are now good.
"I don't think there will be a better opportunity to beat Australia," Rahim told reporters in Dhaka late on Monday.
Bangladesh will host Australia for the first test from October 9-13 in Chittagong and for the second from October 17-21 in Dhaka.
Rahim pointed to recent successes against South Africa, India and Pakistan at home in one-day international series which have propelled Bangladesh to sixth in the ODI world rankings.
