Despite the absence of struggling captain Rohit Sharma, India's top order again crumbled as it reached 57-3 at lunch on the first day of the decisive fifth and final test against Australia at the Sydney Cricket Ground on Friday.

Sharma was replaced as skipper by Jasprit Bumrah, who earlier won the toss and batted on a green-tinged SCG wicket under overcast skies.

Bumrah's decision appeared to backfire early on as the tourists lost KL Rahul and Jaiswal Yashasvi in the first eight overs and then very nearly Virat Kohli also, only for a a contentious TV umpire decision to save the star batter.

Nathan Lyon saw the hosts go to the break the happier when he snared Shubman Gill with the final ball before lunch.

At the break, Kohli was 12 not out.

The start of the fifth test mirrored the four previous it as the bowlers dominated early.

After several deliveries beat the edge of the bat outside off-stump, Mitchell Starc (1-24) found more joy bowling straighter as Rahul (4) chipped a simple catch to Sam Konstas at square leg in the fifth over when India was 11-1.

Scott Boland (1-5) was then introduced into the attack and only needed four balls at Jaiswal (10) to have the young opener edge a ball through to debutant Beau Webster at third slip to reduce the tourists to a shaky 17-2.

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That brought Kohli, the series' pantomime villain, to the crease. Kohli was greeted by booing from many in the the SCG crowd, stemming from his deliberate shoulder bump on Konstas on the opening morning of the Boxing Day text for which he was later fined.

And fittingly, his first ball was the most dramatic of the session. Boland drew the edge and it flew low to Steve Smith's right hand at second slip. Smith appeared to get his hand just under the ball before it hit the ground and the ball popped up for Marnus Labuschagne to complete the catch, sparking wild celebrations for the hosts.

The catch was referred to TV umpire Joel Wilson with replays suggesting the ball may have touched the grass as it came out of Smith hand and Kohli survived.

As lunch approached, Lyon (1-1) was introduced into the attack and in his second over he had Gill (20) edging through to Smith who took a clean catch at chest-height to end the session.

Australia made one change to its team that clinched a dramatic 184-run win at the Melbourne Cricket Ground on Monday to take a 2-1 series lead with allrounder Mitch Marsh dropped for Webster to make a test debut.

Australia leads the series 2-1 and must avoid defeat to regain the Border-Gavaskar trophy for the first time since 2014-15. A win by India and a drawn series at 2-2 would allow the visitors to retain the trophy for a record-extending fifth consecutive time.

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A win for Australia at the SCG would book the team’s spot in a second straight World Test Championship final. Australia beat India in the 2023 decider.

South Africa became the first team to qualify for the WTC final at Lord’s in June by winning a dramatic match at home to Pakistan last weekend.

India drop skipper Sharma

Intense speculation that Sharma would be dropped for the final test was confirmed shortly before play with Bumrah named as India's captain.

With scores of 3, 6, 10, 3 and 9 at an average of 6.2 for the series, Sharma has had a wretched tour since coming back into the side for the second test after he missed India’s comprehensive first-test win in Perth on paternity leave.

While the India team said Sharma had been “rested," the 37-year-old's test career would now appear in peril.