The cricket world had assumed that South Africa would only get their chance to go top of ICC's Test Championship when their back-to-back series against Australia kick off in mid-December. But events in Perth mean they could usurp the Aussies without even taking the field. If New Zealand go on to win the third Test, and thus steal one of the most odds-defying series victories in history, Australia will slip to second place in the table for the first time since Wisden launched it in November 1996. South Africa, who briefly led the Championship in its early days, would again be outright leaders.

The maths go like this. Defeat for Australia would cost them the two points they retained in 1997-98 when they beat New Zealand 2-0 at home. This would dent their points average by 0.16, taking it from a world-beating 1.62 to a more mortal 1.46 – and, crucially, less than South Africa's 1.50.

But a draw at Perth would be enough to postpone South Africa's challenge until December 14, when the sides meet in the first Test at Adelaide. Australia would then be left with an average of 1.54. An unlikely Aussie victory over New Zealand and nothing changes.

Assuming Australia fail to beat New Zealand, all South Africa need to do to regain the No. 1 spot is to avoid defeat in one of the two series against the Aussies. This sounds harsh, but because South Africa's results on the ICC table include home and away defeats by Australia, South Africa have everything to gain – and nothing to lose.

Suddenly, Steve Waugh's reign looks anything but untouchable.

Lawrence Booth is assistant editor of Wisden.com.

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