Despite South Africa's strong fightback late on the third day, thanks to Neil McKenzie and Mark Boucher, there were two promising developments for Australia as this Test passed its midway point. First was the form of Glenn McGrath. Second the revelation of why Shane Warne likes to work alone - or rather with McGrath instead of Stuart MacGill. McGrath starts every home season slowly. He seems lethargic in early games for his state, lethargic enough to have a few in the hierarchy concerned that he lacks interest at that level. Normally McGrath is back on song by the second Test of the summer, if not after his first spell of the first match. In the previous series against New Zealand, McGrath only gained some zip and movement in the third Test.

But in this opening match against South Africa, McGrath has been a different bowler, a more familiar weapon, right from his first spell. The swing and seam were back and, as he showed today with the great delivery that dismissed Jacques Kallis, the reverse-swinging yorker was working beautifully as well.

Now Steve Waugh can proceed, secure in the knowledge that his best bowler is back near his best. South Africa's batting strength is in the top three and they will be tested by Australia's spearhead.

With McGrath back on song, Waugh was able to revert to his most tried and trusted ploy – using the great quick and the great legspinner in tandem. The two build pressure by bowling tight yet still trying for wickets. Their crucial spell in the middle of the day earned the key wickets of Herschelle Gibbs - frustrated and beaten by Warne – and Kallis - leg-before to that McGrath snorter.

As much as any threat to his beloved place in the team, Warne does not like bowling with MacGill because he can loosen the grip with a poor delivery and can also serve to familiarise batsmen with legspin.

Both these great bowlers analyse batsmen within seconds and the contrast between the insistent, aggressive McGrath and the wily, spinning Warne wears away at the best batsmen.

South Africa will not lie down, but it is apparent now that Australia's two most senior bowlers have risen to the challenge.

Mark Ray has covered Australian cricket since 1987 and is also the author of a number of books on the game.

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