Australia build on Konstas's explosive start at MCG

Usman Khawaja, 19 years Konstas's senior, posted his first half-century since January after a dismal start to the series that cast doubt on his international future.

Khawaja fell for 57 in soft fashion 30 minutes before the break, with Marnus Labuschagne (44no) and Steve Smith (10no) to begin the final session. 

But it was 19-year-old Konstas who stole the show in front of a bumper crowd, boldly taking it to the megastars of Indian cricket.

The right-hander showed nerves of steel on debut by attacking Jasprit Bumrah - the world's No.1 ranked bowler who took 21 wickets during the first three Tests to repeatedly destroy Australia's top order.

Teenage star Sam Konstas cut a relaxed figure as he lined up with teammates before his debut Test. (Joel Carrett/AAP PHOTOS)

Konstas was lbw for 60 from 65 balls, 30 minutes before lunch to star spinner Ravindra Jadeja, but not before putting together an innings that will go down in Australian cricket folklore.

Konstas and Khawaja's stand of 89 was the highest by an Australian opening pair during this series.

Coming in for axed opener Nathan McSweeney, Konstas survived a brutal first over from Bumrah when he played and missed four times, before rattling India.

The 19-year-old's first runs, a two off his legs, were cheered like he had reached a milestone, before launching in extraordinary fashion.

Konstas took India's most important player for 14 runs, including a six, off one jaw-dropping over that comprised all ramp shots.

Sam Konstas showed no sign of Test debut nerves with an array of audacious shots. (Joel Carrett/AAP PHOTOS)

By the ninth over, India had reverted to putting fielders out to the boundary in a bid to tame the NSW whiz kid's attacking attitude.

"Bumrah's obviously a world-class bowler, just trying to put pressure on him, trying to change his tactics was the main thing," Konstas told the Seven Network.

Virat Kohli, one of India's most famous cricketers ever, bumped into the teenager during a dramatic mid-pitch incident at the start of the 10th over.

Khawaja tried to defuse the situation by putting an arm around Kohli and laughing it off, but the incident will be closely looked at by the match referee.

A villain of the Australian crowds this summer, India fast bowler Mohammed Siraj fired off words to Konstas multiple times, but he remained unfazed.

Konstas reached his fifty in just 52 balls with a range of shots that are rarely attempted at Test level, especially not a youngster on debut.

It was the third-fastest 50 by an Australian on Test debut, only behind Adam Gilchrist (1999) and Ashton Agar (2013).

Usman Khawaja joined in the batting attack with his best score of the series. (Joel Carrett/AAP PHOTOS)

The country's 468th male Test cricketer, Konstas was presented with his baggy green cap by storied former Australia captain Mark Taylor.

With a beaming smile during the national anthem before the match, Konstas strode to the wicket well in front of Khawaja, determined to face the first ball.

He is the fourth youngest Australian male to play at Test level.

Konstas's innings evoked memories of former star opener David Warner's international debut, coming at the MCG against South Africa in 2009.

But while Warner did it in a Twenty20, Konstas made his mark on the biggest day on the Australian cricket calendar when the Border-Gavaskar series is still delicately poised at 1-1.

Australia must win at least one of the the last two Tests and prevent India from winning again to regain the Border-Gavaskar trophy.

Cummins was 18 when he made his Test debut and he has impressed on Konstas the need to enjoy the moment and not be overawed.

"There's a level of naivety, that you just want to go out and play, like you did when you were a kid in the backyard," Cummins said.

Travis Head, Australia's most important player, passed a Christmas morning fitness test and is in the side, while Scott Boland replaced fellow paceman Josh Hazlewood, who is out of the series.

Boland returns to his home ground and the venue of his famous Test debut when he tore through England with 6-7.

Under-fire captain Rohit Sharma will move back to the top of the order after batting at No.6 in Adelaide and Brisbane.