India are looking to leapfrog South Africa and return to the top of the table with their sixth consecutive win.
Rahul was on his haunches after the winning shot and then had a wry smile as he shook hands with the Australian players.
Gill and Iyer added 200 for the second wicket.
Iyer mised India's second consecutive game in the Asia Cup after being advised rest for the Super Fur contest against Sri Lanka.
The return of Rahul has widened the pool of players to select from, but that has also given the Indian team management a happy headache.
Kuldeep Yadav is the lone frontline wrist-spinner in the Rohit Sharma-led squad, which contains spin all-rounders Ravindra Jadeja and Axar Patel.
None of the Indian top-order batters can roll their arms over and the fact that the likes of Bumrah, Shami, Siraj and Kuldeep hardly contribute with the bat could hurt India big time in a pressure-game.
As per a report in The Indian Express, Tilak Varma and Prasidh Krishna, currently in Sri Lanka for the Asia Cup, where Sanju is a travelling reserve, also miss out on a spot in the World Cup squad.
In place of Rahul, Shastri would like to see rookie batter Tilak Varma in the middle order.
Shreyas Iyer and K L Rahul have resumed batting in the nets but are not certainties for the Asia Cup beginning in Multan later this month.