By Martin Gough
BBC Sport in St Lucia
MATTHEW HAYDEN v SHAUN POLLOCK
In his first meeting with South Africa of this tournament, an 83-run group-stage victory in St Kitts, Hayden set a record for the fastest ever World Cup century, taking just 66 balls.
Meanwhile, Pollock described the day as "my toughest day at the office" after his 10 overs were taken for 83 runs.
The fact that his economy rate of 3.54 is better than any Australian bowler is testament to how well the former South Africa captain has recovered.
Hayden, the leading scorer in the tournament with 580 runs so far, will look to bully Pollock early on to disrupt his rhythm.
To curb him, the veteran bowler will not try anything fancy, simply aim to up his tally of maidens from his current nine - second best in the World Cup - to build pressure and force mistakes.
MIKE HUSSEY v ANDREW HALL
Hall, South Africa's leading wicket-taker with 14, had Hussey caught in the deep in St Kitts but Australia were already well on their way to a total of 377 by then.
This time, if South Africa manage to take early wickets, there will be more pressure on Hussey - Australia's 'finisher' - to keep the scoreboard moving.
However, the dominance of the top-order at the beginning of the tournament left Hussey short of time in the middle and he has managed just 87 runs from six innings so far.
Hall comes into his own in his second and third spells as he gains reverse swing and has an array of slower balls, yorkers and cutters.
BRAD HOGG v JACQUES KALLIS
Left-arm wrist-spinner Hogg has been the surprise of the tournament as he is one of three bowlers - the others are Muttiah Muralitharan and Shaun Tait - with 19 wickets.
He could pose problems for the whole of the South African line-up, who are generally tentative against slower bowling.
But there will be extra pressure on Kallis, even though he is joint-second among World Cup run-makers with 480 at the Bradman-like average of 96.
Kallis was forced to review his approach after he was blamed for the St Kitts defeat, taking 63 balls over his 48 when South Africa needed to score at seven runs per over.
GLENN MCGRATH v GRAEME SMITH
Possibly just two games away from retirement, McGrath is still performing at the highest level, as the World Cup's leading wicket-taker with 22. His average of 14.00 is behind only Shane Bond of New Zealand.
Australia have generally used him as an early first-change bowler, replacing Tait after three or four overs.
However, he has shown signs of being vulnerable if he is attacked and Smith, along with opening partner AB de Villiers, will aim to do just that.
The South Africa captain is one of 10 players in this tournament with a strike-rate of more than a run a ball and has already shared in three century partnerships, the first a stand of 160 against the Aussies.
Smith will be battling the pain of an injured left knee and will be conscious of a need to stay well hydrated after cramps forced him to retire hurt against Australia last time, providing a turning point in the match.