India captain Virat Kohli on Friday said the number four slot in the batting line-up is still to be "solidified", months after he backed Ambati Rayudu for the position till this year's World Cup.

The skipper said that there has been a lot of experimentation at number four, and while the batting line-up at Adelaide, where Rayudu batted at four, was an ideal one, they would like to keep things mixed up until someone assumed responsibility at number four.

"If you look at that last game, Ambati Rayudu batted at four, Dhoni at five and Dinesh Karthik at six. Because we brought in Vijay Shankar and Kedar Jadhav, we didn't want Karthik to change his spot because he is doing a good job," he said after the third and final ODI of a historic tour of Australia.

Rayudu was backed for the position by Kohli during the home series against West Indies last year.

"...The middle order we saw in Adelaide is pretty much the most balanced if you look at it. The number four position, again, has been a sort of an area which we want solidified," he said.

"But because of the combinations we want to play, sometimes you have to make those changes. Anyone who bats at four will have to take the responsibility for the World Cup, whoever it might be. That person will have to take responsibility at number four," he added.

The skipper credited the victory to Yuzvendra Chahal, who picked up the best figures for an Indian spinner on Australia soil and restricted the hosts to a low total.

"...Taking six wickets at the MCG is no small feat for a spinner. He is very intelligent bowler and he gets us those breakthroughs. He and Kuldeep are definitely a force to be reckoned with. When they play together, it is our most potent spin attack...," he added.