The Australia team will not be released until Thursday but the reports said Fox Sports TV, also owned by the media group and an official broadcast partner of the Australian Rugby Union, "understood" the 32-year-old would start against the Lions.
That the team for the first test was leaked a day before the official announcement lends credence to the reports, which also said Michael Hooper, who played the first two Tests in the number seven shirt, would drop to the bench.
Once one of the best openside flankers in the world, Smith retired from international rugby at the end of 2010 after making 110 appearances for Australia - including all three Tests against the 2001 British Lions.
After storming back into contention for this year's Lions tour on the back of some brilliant performances for the ACT Brumbies, he was stricken with a knee injury on the eve of the initial squad announcement.
A remarkably quick recovery saw him called into the squad after the first Test defeat in Brisbane but he was not considered for last Saturday's second Test in Melbourne, which the Wallabies won to level the series.
Coach Robbie Deans said on Tuesday that Smith was fit and available for selection for the third Test without being drawn on whether he was likely to be included in the team.
Loose forward Ben McCalman was earlier confirmed by team officials as a surprise inclusion in the 23-strong matchday squad for the Test.
Liam Gill, the third openside in the squad, looks likely to miss out, a tough call on a player whose late line-out steal played a major role in Australia winning the second Test last weekend.
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