ICC Champions Trophy, Johannesburg:
Australia 275-8 (50 ovs) beat West Indies 225-9 (46.5 overs) by 50 runs
Left-hander Johnson hit three sixes in his brutal innings
Mitchell Johnson's unbeaten 73 from 47 balls proved crucial as Australia beat West Indies by 50 runs in their opening Champions Trophy match in Johannesburg.
Skipper Ricky Ponting hit 79 before his side slumped to 171-7 in the 40th over.
However, number eight Johnson smashed three sixes and eight fours to help the reigning champions to 275-8 in Group A.
Andre Fletcher (54) and Travis Dowlin (55) gave the underdogs hope but they ran out of steam and finished on 225-9, with Dale Richards unable to bat.
Their second defeat means West Indies, who are fielding a weakened side because of a pay dispute between the players and their cricket board, are effectively out of the tournament.
Australia, however, take on India on Monday with high hopes of reaching the last four, although Ponting said his side would have to play better.
"Today we had a few too many extras. We expected the new ball to do a bit more for us than it did and the bowlers probably got a little bit carried away with that," he said.
"The ball seamed around a lot in the morning and we ended up batting on a pretty difficult wicket. To get that total, I thought the batsman did a really good job and Mitch finished things off really well," he added.
Darren Sammy dismisses James Hopes to reduce Australia to 171-7
West Indies captain Floyd Reifer admitted that Johnson's brutal knock had changed the course of the match.
"We had Australia 170-odd for seven but the game was taken away from us in the last 10 overs. Mitchell Johnson played well and Brett Lee also played a pretty good innings," he said.
Australia, fresh from a 6-1 thrashing of England, got off to a terrible start when Shane Watson was bowled off the first ball of the game from Kemar Roach.
Tim Paine was dropped by fellow wicketkeeper Chadwick Walton on 16 but was eventually out for 33, from 59 balls.
Ponting brought up his fifty from 62 balls but Mike Hussey's departure for six put the West Indies on top.
Nikita Miller secured the key wicket when he had Ponting stumped and the spinner then turned one through Cameron White's defences.
Roach bowled Callum Ferguson and Darren Sammy saw off James Hopes to leave Australia struggling on 171-7 in the 40th over.
But Johnson and Brett Lee put on 70 from 52 balls to reignite the innings, with Johnson smashing two sixes over mid-wicket off Sammy as he recorded his first one-day international half-century.
Lee was run out for 25 after attempting a third run but Johnson and Nathan Hauritz smashed 32 off the last two overs to get Australia to an imposing total.
Fletcher and Dowlin put on 86 for the second wicket but Australia got the vital breakthrough when Fletcher was run out by a direct hit from Johnson at mid-off.
Dowlin made his way to a patient 55 off 87 balls before he top-edged a delivery from Lee, and no-one else was able to make an impact as Australia wrapped up victory.