In a devastating display of power and technique, Gilchrist, revelling in his role as acting captain and playing in front of his home crowd, feasted on the Sri Lankan bowling and smashed his way out of a form slump with four sixes and 10 boundaries.

His stunning century, which came up in only 99 balls, in partnership with fellow opener Simon Katich, carried Australia to 237-4 off 41 overs in reply to Sri Lanka's pedestrian 233-8 off 50.

Gilchrist had not reached 50 in his last seven one-day innings and his relief was obvious as he punched the air and ran towards his teammates in the dressing rooms in celebration.

When he finally fell, caught and bowled by veteran spinner Muttiah Muralitharan, Australia had lost their first wicket with 191 runs on the board.

Katich took the backseat in the partnership but still clocked up his second successive half-century finishing with 82 off 110 balls before he was bowled by Chaminda Vaas.

It was a formidable display by the Australians, who are now guaranteed a place in the best of three finals series, even though they failed to collect a bonus point by not winning inside 40 overs.

Australia now have 18 points after six matches -- nine points clear of Sri Lanka who have also played six.

South Africa, who play Sri Lanka in Perth on Tuesday, have eight points from just four matches.

The Sri Lankans never looked in the hunt on Sunday and it was obvious from the outset that the Australians meant business.

At one point Gilchrist humiliated super-sub Akalanka Ganega-max taking 20 runs off what was to be his only over.

The Sri Lankans had earlier crashed to 27-3 in the 11th over of their innings and were only saved from disaster by a fourth-wicket partnership of 121 off 156 balls between Mahela Jayawardene and Russel Arnold.