Lokesh Rahul and Rohit Sharma remained unbeaten to take India to 71/1 at stumps.Mitchell Starc struck in the first over of India’s reply to Australia’s imposing 572 for 7 declared before Rohit Sharma and Lokesh Rahul combined to guide the visitors to 71 for 1 at stumps on Wednesday on the second day of the fourth Test.Australia declared just after tea with their top six batsmen all scoring above 50, including centuries for Steve Smith (117) and David Warner (101), and then Starc took the first wicket without a run on the board when he had Murali Vijay caught behind. But Sharma (40 not out) and Rahul (31 not out) ensured there was no further damage for India in the last session, cutting the first-innings deficit to 501.Bat has dominated ball in every session so far at the Sydney Cricket Ground. Smith continued his fine form, scoring his fourth century in as many Tests and sharing a 196-run partnership with Shane Watson (81).His milestone matched the marks of Don Bradman (vs South Africa in 1931-32) and Jacques Kallis (vs West Indies in 2003-04) in scoring four hundreds in four consecutive Tests in a series. Smith, promoted to the Test captaincy due to Michael Clarke’s latest recurrence of back and hamstring trouble, leads the scoring this series with 698 runs at an average of 139.6.Only Bradman (715 runs in 1947-48) and Ricky Ponting (706 runs in 2003-04) have scored more runs in a series between Australia and India.Umesh Yadav (1 for 137) eventually dismissed Smith for 117 caught behind when Australia had reached 400. Watson again failed to convert a promising start into a century when he heaved a short-pitched Mohammad Shami (5 for 112) delivery straight to deep midwicket where Ravichandran Ashwin made no mistake taking the catch – he dropped Watson on the penultimate ball of day one.advertisementWatson has 24 half-centuries to go with only four Test hundreds in his 55 Tests. With Shaun Marsh (73) and Joe Burns (58) adding half-centuries, Australia set a benchmark with their top six batsmen all passing 50 in the same Test for the first time.Marsh had two reprieves before he as acrobatically caught by wicketkeeper Wriddhiman Saha off Shami’s bowling. Burns offered good support to post his first Test half-century before lofting a catch to Rahul in the outfield off Shami as Australia chased quick runs to end its innings.Ryan Harris produced a brief cameo, belting 25 off nine balls before Shami had him caught by Ashwin for his fifth wicket and prompted Smith’s declaration.On the first day, David Warner smashed 101 and Chris Rogers made 95 after Smith won the toss and chose to bat first. Australia have an unassailable 2-0 series lead, and regained the Border-Gavaskar trophy, with two wins and a draw in the first three Tests.