Stand-in batsman Adam Voges hit a maiden ODI century to lift Australia to a fighting 274 for five in the fifth and final match against the West Indies at the MCG.
Batting at number five, the 33-year-old brought up his ton off 98 balls and ended unbeaten on 112.
Voges only came in at the last minute to replace the injured George Bailey but played the star role despite being a fringe player in the six years since he made his debut.
West Indies, seeking to avoid a 5-0 series whitewash, had Australia at 2-2 as Tino Best cleaned up the openers.
When Voges came in they were just three for 63 and a high total looked unlikely with skipper Michael Clarke also on the injured list with hamstring trouble.
But Voges looked in fine form and cracked a six to bring up a 100 partnership with veteran Brad Haddin.
The wicket-keeper changed the game by attacking the bowlers from the outset, hitting successive boundaries off West Indies captain Darren Sammy in the 30th over to relieve the pressure.
Haddin skied a top edge off Kemar Roach to Kieran Powell in the deep when he had made 43 off 45 balls out of a vital partnership of 111 with Voges.
The West Australian went on to post his finest ODI total after Darren Sammy had put him down at slip off spinner Sunil Narine when on seven.
All-rounder James Faulkner accompanied him through the final overs, adding a quickfire 31 off 24 balls to set the tourists 275 to win their first match of the series. The final partnership put on 81 runs from 51 balls.
West Indies had looked in control in the opening stages when Tino Best bowled replacement captain Shane Watson first ball.
Aaron Finch then top-edged a Best bouncer to Sunil Narine at fine leg on the boundary in the third over for just one run.
Shaun Marsh, in for Clarke, found the first boundary in the fifth over.
But Best and Sammy were restricting Australia, bowling the new ball at speeds peaking over 150 kilometres per hour (93 mph).
Phillip Hughes faced 19 balls before he got a run but patiently built a partnership of 61 with Marsh before D.J Bravo had him caught for 29 off 61 balls.
Pollard took the freak leaping catch at backward point, knocking the ball into the air with an outstretched left hand and holding it easily at second bite.
Keeper Devon Thomas made no mistake in snapping up Shaun Marsh, who had reached 40 off 58 balls and was looking set at the start of the 25th over. It was Dwayne Bravo's 150th ODI wicket.