Adam Gilchrist belted the fastest one-day century by an Australian to spearhead the world champions to this season's tri-series crown at the Gabba.

Gilchrist brought up his 14th limited-overs ton in just 67 balls to make mince meat of Sri Lanka's total of 9-266 in the third and deciding final.

His blazing knock of 122 (91 balls) ensured Australia became just the fifth team in the 27-year history of the triangular tournament to fight back from a 1-0 finals deficit to win.

The keeper-batsman bashed 13 fours and four sixes as he and Simon Katich (107 not out) amassed a record 196-run opening stand against Sri Lanka to cruise to a nine-wicket victory in the 46th over.

Katich, under immense pressure from Phil Jaques to keep his place for the upcoming tour of South Africa, played the perfect foil to his fellow left-hander for his maiden ton.

The one-day tour squad will be named on Wednesday but the effort may have left selectors with red faces as they had already signed off on the party before he went to the crease on Tuesday.

Gilchrist, given a life by Sanath Jayasuriya on 20, made Sri Lanka pay dearly for a swirling missed skier off Ruchira Perera.

His century was the equal sixth fastest of all time and required six balls less than his previous Australian record of 73 balls for his century against the World XI at Telstra Dome in October.

Gilchrist's second swashbuckling century in five matches marks a remarkable turnaround for the vice-captain since his last visit to Brisbane.

He left the Gabba four weeks ago with his tired head low after a first-ball duck, 24 runs from his previous five one-day bats and a dissent citing after clashing with umpire Aleem Dar.

At the time selectors decided to give him a two-match rest designed to refresh and recharge the batteries.

It has certainly done the trick and made calls for his axing look utterly ridiculous.

The only halt to Australia's charge was provided by some sections of the 26,139-strong crowd which protested new spectator restrictions with a continuous Mexican wave that saw rubbish rain onto the outfield.

With fellow veteran Glenn McGrath unavailable for the six-match South African series, pacemen Nathan Bracken and Stuart Clark showed they were ready to step into the breach.

Bracken (3-44), gaining good swing with the new ball, reduced the tourists to 2-28 in the eighth over after they won the toss and batted on a good track.

They could have been in worse trouble but Katich and Mick Lewis both missed regulation catches in the field.

Mahela Jayawardene (86 off 91), Russel Arnold (76 off 70) and Kumar Sangakkara (59 off 85) then punished the errors and grabbed the ascendancy at 3-200 after 40 overs.

But Clark (2-45) choked up the run-flow by taking 2-1 with three balls including Jayawardene, who squeezed a full ball to Katich at point.

The crowd was given extra value for their money with Ricky Ponting and Andrew Symonds pulling off sensational outfield catches.

Symonds' third grab of the innings - a diving effort at deep cover to dismiss Chamara Kapugedera (9) - was his best but it paled in comparison with Ponting's belief-defying lunging overhead catch.

The skipper's one-handed grab while running backwards with the flight of the ball evoked memories of John Dyson's goalkeeper-like leap at the SCG in 1982.

Gilchrist was named man of the match while all-rounder Symonds was given the man of the series award.

Sri Lankan coach Tom Moody felt his side's total could have been a winning total.

"We thought it was a competitive score but when someone like Adam Gilchrist goes off no score is a par score," Moody told ABC Radio.

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