South Africa and Sri Lanka will fight it out on Tuesday for a place in the VB Series finals, after the Proteas were convincingly beaten by Australia at the Sydney Cricket Ground on Sunday.
South Africa needed a victory to cement a finals berth but were unable to chase down the mammoth 345-run target set by Australia in the 11th match of the series.
The visitors' run-chase faltered early when Australian speedster Brett Lee claimed the vital wicket of opener Graeme Smith (6) in the third over, the South African skipper edging through to an outstretched Adam Gilchrist.
Opener Boeta Dippenaar then combined for a 45-run partnership with new batsman Herschelle Gibbs as the pair attempted to keep in line with the target.
But when Dippenaar put up a towering ball that was caught by a scrambling Michael Hussey, the Proteas were 2-52. Gibbs and Mark Boucher then settled down for a 52-run stand, but the run-rate was ballooning out of control.
When Symonds snared the valuable wicket of Gibbs (46) just shy of his half-century, South Africa slipped to 3-105.
Boucher (76) kept up the fight with a hard-hitting half-century that included three fours and two sixes, the wicketkeeper looking undaunted by the Australian bowlers, before a mistimed shot saw him hand super-sub Hopes a catch at long-off, and all but ending South Africa's slim chance of victory.
Ashwell Prince (25) made the mistake of testing Ponting's arm in the field with a quick single - the Australian skipper threw down the stumps and Prince continued running to the pavilion.
Johan van der Wath (37 no off 16 balls) and Jacques Rudolph (31 no off 39) made a last-ditch effort with some huge hitting, but it was all in vein as time ran out and the prospect of missing the finals became a reality for the Proteas.
Earlier, Adam Gilchrist (88), Ricky Ponting (72) and Damien Martyn (79) all smashed stunning half-centuries as they laid the foundation for a massive innings, re-affirming Ponting's decision to bat first on the quick wicket.
Gilchrist belted 14 fours and was on target for one of the quickest centuries before his dismissal, the Aussies peppering the boundary with 33 fours from their 50 overs.