"They've played some very good cricket in this tournament, being unbeaten, while we've had a few hiccups along the way," said Kallis.
"But now it all doesn't mean much. There's all the hype before the game but carrying your points through doesn't count for anything in a semi-final. It's a game where who produces the goods on the day will win."
Kallis said both teams would go into the match with high expectations.
"They'll carry a lot of confidence through because of the way they've played but we're also confident after a massive win against England."
Staying calm will be a focus of the South African team, according to Kallis.
"There's no need to stress the importance of the game. It's important that we stay relaxed and calm. From our perspective the trip to the Caribbean has been a positive thing.
"We've had some pressure situations, like when we faced possible elimination in the match against England. We've had some other close calls to deal with and we've managed to stay calm throughout."
Kallis is one of four survivors from the dramatic tied semi-final against Australia at the 1999 World Cup in Birmingham, together with former captain Shaun Pollock, wicketkeeper Mark Boucher and batsman Herschelle Gibbs.
All four said after a team practice Saturday that they believed the experience of playing in what at the time was rated the greatest one-day game of all time would have positive benefits.
"From our side we gained a lot of experience in that game," said Kallis.
"Looking back there are a few things that we might have tried to do differently so the experience we've carried around for all these years will probably stand us in good stead."
Opening bowler Pollock said he was looking forward to the challenge of trying to contain or dismiss Australia's hard-hitting top order batsmen.
"We've had some close encounters against Australia and we've learnt from those," said Pollock.
"It's the kind of challenge that you want to play cricket for. You want to come up against the best and if you can win the battle it gives you real satisfaction. "
Gibbs said there was no pressure on the South Africans.
"Our backs were against the wall (before the game against England). Now we're just going to go out there and enjoy it."
Kallis said the players weren't sure what to expect from the pitch in St Lucia but were keen to win through and play in next Saturday's final in Barbados following their crushing nine-wicket win over England there.
"We'll look forward to coming back to Barbados for the final. Of all the wickets we've played on this is the most similar to home," said Kallis.
"We haven't played the consistent cricket we would have liked but I think we have peaked at the right time.
"We've beaten Australia in the past and they've beaten us. It will be the side that is the most relaxed on the day and wins the key overs that will win the match," he said.