Group A, Potchefstroom: Australia 301-6 (50 overs) beat Namibia 45 all out (14 overs) by 256 runs
Records came tumbling down in Potchefstroom as Glenn McGrath guided Australia to a crushing win over minnows Namibia.
McGrath ripped through Namibia's batting order to lead the reigning champions to a whopping 256-run victory - the biggest ever winning margin in the history of the World Cup
The paceman completed bowling figures of seven for 15 - the best ever at the tournament - helping to bowl out Namibia for 45 in just 14 overs.
The result means Ricky Ponting's team -who now share a record 11 consecutive wins with West Indies between 1984 and 1985 - will definitely qualify for the Super Six stage as Group A winners.
Earlier, Darren Lehmann and Brad Hogg shared a quickfire seventh-wicket partnership of 70 as Australia finished their innings 301 for six.
Australia looked at ease in Potchefstroom, but found themselves caught offguard on several occasions by their plucky opponents.
Medium-pacer Louis Burger was the pick of the Namibian attack with three wickets for 39, including the scalp of Matthew Hayden.
The 24-year-old removed Michael Bevan (17), Hayden (88 off 73 balls) and Ricky Ponting (two) in quick succession before Andrew Symonds (59) and Damien Martyn (35) shared a fifth-wicket partnership of 84.
Later, Lehmann took a World Cup record 28 runs off Rudi van Vuuren's last over of the innings to finish unbeaten on 50 from 31 balls and set a hefty total for Australia.
1. G McGrath (Australia) - 7-15 v Namibia 2003
2. W Davis (West Indies) - 7-51 v Australia 1983
3. G Gilmour (Australia) - 6-14 v England 1975
4. A Nehra (India) - 6-23 v England 2003
5. C Vaas (Sri Lanka) - 6-25 v Bangladesh 2003
Facing a near impossible target of 302, cricketing minnows Namibia had little chance against the ferocious Australian attack led by McGrath.
He removed Jan-Berry Burger, Morne Karg, Gavin Murgatroyd, Danie Keulder, Louis Burger, Deon Kotze and Bjorn Kotze in quick succession to claim the best one-day
international figures of his career.
Only one player, captain Deon Kotze, reached double figures with 15 as Namibia slumped the second lowest totalat the tournament - much to the delight of Australia.
Comfortable victories over Pakistan, India, Holland and Zimbabwe have already guaranteed Australia's presence in the Super Six stage, but the team will be oozing with confidence after their latest crushing win.
Australia: Ricky Ponting (captain), Adam Gilchrist, Matthew Hayden, Damien Martyn, Darren Lehmann, Michael Bevan, Andrew Symonds, Brad Hogg, Brett Lee, Jason Gillespie, Glenn McGrath.
Namibia: Deon Kotze (capt), Jan Burger, Louis Burger, Morne Karg, Daniel Keulder, Bjorn Kotze, Gavin Murgatroyd, Stefan Swanepoel, Burton van Rooi, Melt van Schoor, Rudi van Vuuren
Umpires: Russel Tiffin (Zim) and Billy Bowden (Nzl)
TV umpire: Neil Mallender (Eng)
Match referee: Gundappa Viswanath (Ind)