In the process the West Indians, with nine points in three matches, also booked themselves a berth in the final. Australia have seven points in three matches while India are at the bottom with just two points from as many outings.
Scorecard of Match 4
The Men in Blue now have an uphill task of winning both of their remaining matches and stay in the hunt at the cost of Australia.
It was a skippers' day all the way at Kinrara Oval today. Led by stand-in skipper Michael Hussey's century Australia posted a daunting total of 272 runs. But Brian Lara was imperious and guided the West Indies to overhaul the target with 16 balls to spare.
The West Indians floundered in the beginning and lost two wickets for 44 runs. However, Lara and Chris Gayle added 151 runs for third wicket to turn the table on to the World Champions.
West Indies start was not auspicious as they lost in-form batsman Shivnarine Chanderpaul early caught behind off Brett Lee.
Vice captain Ramnaresh Sarwan looked in good nick but couldn't build on to his start throwing his wicket away to Bracken.
It was attacking batting on display all the way from skipper Lara and Chris Gayle. Gayle was particularly severe on Stuart Clarke hitting him for tall sixes.
A few hundred spectators at the Kinrara Oval were treated to batsmanship of highest order with Lara not sparing a single corner of the park without hitting the fence.
To young off breaker Dan Cullen Lara just decided to dance down the track for lofted shots and in the process shattered the bowler's confidence.
Lara and Gayle added hundred runs in just 91 balls for third wicket thus bringing down the asking rate well under five.
With the batsmen scoring at free will, all the bowlers felt the heat but none more than Stuart Clarke. Already taken for severe beating Clarke's seventh over proved to be most costly in which he conceded 23 runs.
Clarke was replaced by Shane Watson and the move paid off when Gayle holed out to Hussey at mid-wicket. Australia sensed a chance to get back in the match. But Lara was in no mood to lower guard. He saw off a threatening spell from Brett Lee and when Cullen was brought once again, Lara just came down the pitch to hoist straight over for a six.
However Lara couldn't stay till the end as he miscued a rising delivery from Lee and offered a simple catch at backward point. Lara 87 came off 81 balls with 11 hits to fence.
When he left, 31 runs were needed to win in almost 10 overs and three wickets fell in quick succession but Bravo played a patient knock of 37 to see West Indies through.
Earlier, a fabulous 109 off 90 balls from stand-in captain Mike Hussey took Australia to a healthy total of 272 for six. Australia overcame disastrous start to their innings after electing to bat first. Leading the side in absence of Ricky Ponting who was rested Mike Hussey chose to bat first after winning the toss.
Australia brought in Brett Lee, Andrew Symonds and Mathew Hayden in the playing eleven. West Indies made one change -- Marlon Samuels in place of Fidel Edwards.
But it was not good start for Hussey as Australian skipper as the West Indies bowlers ripped through the top order.
But Katich, who was dropped by Wavell Hinds in the first over, failed to take full advantage of a life as he was ultimately run out for 22. Taylor and Bradshaw bowled tight line and length to stifle the Australian scoring.
The star performer of last match Shane Watson as he returned back on duck. Andrew Symonds (8) who got first match in the series also failed to impress falling to Bradshaw, who also got the better of Michael Clarke (1).
Australia were four for 64 but Mathew Hayden led the Australian fight back with a patient 49. Later Hussey and Brad Haddin, who scored 70, repaired the Australian innings with great success.
Haddin took charge after fifty partnership with his skipper Hussey. He hit a flurry of sixes, with the spinners Gayle and Samuels bearing his brunt.
Skipper Hussey too stood out in this innings showing much maturity in leading his side with responsibility. If Haddin threw his bat around for quick runs, Hussey was more copybook, but not any less effective. His elegant cover drives stood out as also occasional forays in reverse sweep that also fetched him boundaries.
In slog overs, Hussey chanced his arm and hit a straight six off Bravo, while another clip off Taylor cleared the long leg fence.Hussey hit a boundary in the same area next ball to complete his hundred.
Haddin was out in the last over to Bravo not before he had added precious 166 runs for sixth wicket with Hussey.