South Africa, who won the three-Test series against Sri Lanka by 2-1, will be ranked second when the Test Championship table is next updated after the Adelaide Test.
Even if India manage to win the next two Tests against Australia, it will still lose its second place to South Africa.
If the series in Australia ends in a draw, then India and South Africa will be locked at 117 ratings points but the South Africa will be ranked ahead of India when the ratings are calculated beyond the decimal point.
If Australia wins 3-0, it will move to 110 ratings points, two behind India, while a 3-1 series win will mean India will drop to 113 ratings points while Australia will rise to 108 ratings points.
However, if Australia makes a clean sweep of the series, then both sides will be locked at 111 ratings points, but India will still be ranked above Australia by a fraction of a point.