After losing a three-match series of one-day internationals to Pakistan last June, Australia went unbeaten through a limited-overs series against Waqar Younis's side in Kenya and then won 3-0 in the Test series that followed.
Those Test victories included two by an innings, one of them inside two days, but despite those wins, Buchanan said there would be no complacency among his players in what is a re-run of the 1999 World Cup final, which Australia won by eight wickets.
"Yes, our record against them recently is good, but past or even current form counts for very little when you play Pakistan," Buchanan told Reuters on Sunday.
"They have one or two individuals who can turn it on with other players then feeding of them, and that can make them a formidable side."
Buchanan believes the Johannesburg showdown between the two sides could hold significance for the Super Six stage of the tournament which follows the group matches.
"If we can win this match and both sides qualify for the Super Sixes, then we will take the four points we would get through with us, so a win is pretty important," he said.
"The game is also a chance to see where we are at in terms of our preparations and, while I am hoping to win, it would also be nice to get a good hard game under our belts early in the tournament too," he added.
Pakistan coach Richard Pybus echoed Buchanan's thoughts when he said Australia's dominance in recent head-to-head matches meant little coming into the Group A encounter.
STRONGEST SQUAD
"When we played them late last year, we were without Inzamam-ul-Haq, Yousuf Youhana, Saeed Anwar and Wasim Akram, but now this is pretty much the strongest squad Pakistan can put out," said Pybus.
"Also the World Cup is unique and that can mean past form doesn't really count."
Both sides have injury problems, though, with Pakistan opener Anwar still to practise since sustaining a blow to his left elbow from a Shoaib Akhtar delivery in the nets last Tuesday.
Australia, already without suspended batsman Darren Lehmann who is serving the last match of a five-game ban, will also be monitoring the progress of fellow middle-order batsman Michael Bevan as he recovers from a torn groin muscle.
Ian Harvey, a very effective 'bits-and-pieces' player, has a slight back strain, although it is not serious.
Another poser for both line-ups on Tuesday will be which bowlers should take the new ball.
Pakistan have four options in Shoaib, Wasim, Waqar and young fast bowler Mohammad Sami while Australia, with Jason Gillespie and Glenn McGrath both fit again, have to decide whether to retain Brett Lee as their opening bowler.
Lee was hugely impressive when spearheading Australia's attack in the recent triangular one-day series against England and Sri Lanka, ending up as the player of the series.
