Coach Justin Langer has rebuffed Sachin Tendulkar's criticism that Australia's batting is too defensive after the current side ground through a tough second day in Adelaide to remain behind India's first innings.

But Australia's head coach did concede the team was playing to a different standard of scrutiny, exemplified by the enthusiastic antics of India captain Virat Kohli.

India bowlers fightback has Test poised

Kohli was his usual animated self on Friday, celebrating Australian wickets with gusto. Langer said he "loved seeing that passion" but said Australia players would be judged differently if they did the same.

"If we did that at the moment we'd be the worst blokes in the world," Langer said on Fox Cricket. "It's a fine line, isn't it? That's the truth of it. But I love seeing the passion."

Tendulkar lit up social media on Friday by claiming he had never seen such a "defensive mindset" from Australia batters at home, crediting the impact of off-spinner Ravi Ashwin.

#TeamIndia should make the most of this situation and not lose their grip. The defensive mindset by the Australian batsmen at home is something I’ve not seen before in my experience. @ashwinravi99 has been very effective and has played a role to help the team be on top, for now. December 7, 2018

Tendulkar, who played his first match against Australia in 1991, and his last in 2013, faced a different era of Australian cricket compared to the current side that is rebuilding in the wake of March's ball-tampering fiasco in South Africa.

Langer conceded as coach he needed to be "wary" of that criticism and that it "could really hurt us" if the players let it get under their skin.

"The teams that Sachin would have played against started with Allan Border and David Boon, and Steve Waugh and Mark Waugh, and Ricky Ponting," he told Fox Cricket. "Guys that had great Test match experience and they knew their game, were comfortable in their own skin and they knew what to expect.

"Whereas we've got a team at the moment who are very inexperienced in Test match cricket, particularly our batting side.

QUICK SINGLE Cool Head prevails as India battle back

"They're just fighting as hard as they can, they're fighting their backsides off, they're always looking to score but the wicket is tough, and it's a slow outfield.

"That's the beauty of Test cricket, it's bloody hard work.

"We have to be patient with them. You can't give these guys 30 or 50 matches of Test match experience. They have to earn it."

Langer said the slow scoring rate owed much to the Adelaide Oval surface, one he declared "a brilliant Test wicket".

"But go back a day, against a very experienced Indian side, and they did the same thing. When they went for their big drives we got them all out," Langer said.

"It's got a lot to do with this wicket, it's got a lot of grass on it … it's really, really hard work, it's nipping around, you never really quite feel like you're in."

Ashwin enjoying bowling in Adelaide

Langer said Australia "could have been a bit more proactive" against Ashwin.

"Particularly our lefities, we need to have methods of scoring on both sides of the wicket," he said.

"There's areas we can get better at, but I'm definitely not getting caught up in this 'we're too slow, we're not attacking enough' business."

Test debutant Marcus Harris, one of four members of Australia's top six to have played less than 15 Tests, scored 26 in his maiden innings, and said the going was tough on " one of those old school, hard days of Test cricket".

We're 100 per cent in the game: Harris

"You want to attack all the time but sometimes it's not that easy," Harris told reporters.

"The wicket wasn't overly easy to score on, and I thought they bowled really well and set some good fields. I think it's pretty even and both teams have bowled pretty well so far.

"You can only put the bowlers under pressure if they give you the opportunity to put them under pressure. You want to come out and blast them everywhere and be going great guns, but sometimes it's not that way. That's why it's called Test cricket.

"We're still fighting, still in the contest."

Domain Test Series v India

Dec 6-10: First Test, Adelaide Oval

Dec 14-18: Second Test, Perth Stadium

Dec 26-30: Third Test, MCG

Jan 3-7: Fourth Test, SCG

Australia squad: Tim Paine (c, wk), Josh Hazlewood (vc), Mitch Marsh (vc), Pat Cummins, Aaron Finch, Peter Handscomb, Marcus Harris, Travis Head, Usman Khawaja, Nathan Lyon, Shaun Marsh, Peter Siddle, Mitchell Starc, Chris Tremain

India squad: Virat Kohli (c), Murali Vijay, KL Rahul, Prithvi Shaw, Cheteshwar Pujara, Ajinkya Rahane, Hanuma Vihari, Rohit Sharma, Rishabh Pant (wk), Parthiv Patel (wk), Ravi Ashwin, Ravi Jadeja, Kuldeep Yadav, Mohammed Shami, Ishant Sharma, Umesh Yadav, Jasprit Bumrah, Bhuvneshwar Kumar