Australia was expected to name its XI today but instead moved it back until before the toss on Thursday.
"It's just team balance really," captain Tim Paine said.
"There's ongoing discussion the last day or two but we'll have a final look at the wicket (this afternoon) and we'll have our last chat then.
"We're not too far away. As I said all along, we'll be looking to pick the best XI that we think is the best combination to win this Test and the wicket will play a part in that."
India's top spinner Ravichandran Ashwin was ruled out of the series-decider on what is expected to be turning wicket - only to be added back to the squad hours later.
"It's unfortunate that he's had two niggles that are quite similar in the last two away tours. He's very important for sure.
"In test cricket, he's a vital part of this team and we wanted him to be 100 per cent fit fora longer period to that he can come back to us in the test format.
"He is very disappointed that he's not able to recover in time," Kohli said of Ashwin before the lanky off-spinner was recalled.
Ashwin, who suffered an abdominal strain on the fourth day of the opening Adelaide test, trained on Tuesday and looked to be in no state to play on Thursday.
The BCCI said a final call on his fitness will be made shortly before the start of play.
In-form seamer Ishant Sharma was bizarrely left out of the squad and will be replaced by Umesh Yadav, while in another blow middle-order batsman Rohit Sharma, who hit a gritty 63 in the first innings of the Melbourne test, has jetted back to Mumbai after his wife gave birth to a daughter.
Australia must win to prevent India, who lead 2-1, claiming a first-ever series triumph Down Under.
