Smith has scored back-to-back centuries for the Sixers in his last two games for the club, having also made a start against the Perth Scorchers in the first game he played.
In reaching triple figures, first making 101 against the Adelaide Strikers, before belting 125 not out against David Warner's Sydney Thunder last night, Smith became the first player in Sixers' history to score a century.
Despite the century against the Thunder, Smith was suffering back spasms late in the game and ultimately was substituted off the field as the men in magenta rolled their cross-town rivals for just 63.
Smith first suffered the spasms as training during the afternoon, and it's unclear if he will be fit to play the Hobart Hurricanes on Monday in the Sixers' final regular season game.
Nathan Lyon has also missed the last two games for the Sixers with knee soreness, and it has raised questions ahead of Australia's tour of India for the Border-Gavaskar trophy, which is set to get underway on February 9 in Nagpur.
Smith said after the win over the Thunder that he expects both he and Lyon to be okay for the first Test however.
"I'm pretty certain we'll be all right," he said.
"I just had some spasming this afternoon.
"I struggle to get upright.
"I can bend (forwards) all right but getting into an extension is not ideal. It probably helped me in my batting, kept me a bit lower.
"It's a bit stiff but hopefully I pull up okay."
Smith, as one of Australia's best players of spin, will be crucial to Australia's chances, who are also set to lock up a World Test Championship final place with just a single draw from the first Test.
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Australia have not won in India since 2003, with Lyon the lead spin bowler for the tour, joined in the 18-man travelling squad by Mitchell Swepson, Ashton Agar and the yet to debut young gun Todd Murphy.