AUSTRALIA'S immediate cricket focus is on the Top End, but a tour of India by emerging players will have a major say on whether the world champions retain the Border-Gavaskar Trophy this year.

While Australia will kick off their season in Darwin with three one-day internationals against minnow Bangladesh, an Australia A squad's tour of India could provide a better form guide to the year's most-anticipated Test series.

A match-winning spinner will be a key in Australia's defence of the Border-Gavaskar Trophy in four Tests against India on the subcontinent in October.

Australia's bowlers were the stars of the series win in India in 2004, but that attack of Glenn McGrath, Jason Gillespie, Michael Kasprowicz and Shane Warne will be spectators this time around.

On top of Warne's absence, the retirements of Stuart MacGill and Brad Hogg present Australia with the headache they must have always feared - entering a series in India without an established Test spinner.

That's why selectors will wait until after the first half of the Australia A tour - which features left-arm wrist-spinner Beau Casson, legspinner Bryce McGain and offspinner Jason Krejza - before they announce the squad to play India.

The Australia A players leave for India tonight. The selectors want to assess the three turners in two three-day matches in Indian conditions to determine the number one candidate.