Australia defeated the West Indies by 50 runs in a Group A Champions Trophy cricket match at New Wanderers stadium in Johannesburg on Saturday. Mitchell Johnson sizzled with an unbeaten 73 runs as Australia began the defence of their Champions Trophy title with a 50-run win over a fighting second-string West Indies.Riding on Johnson's maiden half-century coupled with skipper Ricky Ponting's brilliant 79 Australia rattled up a challenging 275 for eight after sent in to bat. The defending champions bowled out the West Indies for 225 in 46.5 overs. For West Indies A Fletcher 54 and T Dowlin 55 were the main contributor. For Australia Spinner Nathan Hautritz 2 for 23 Peter Siddle 2 for 37 and Shane Watson 2 for 34 shared two wickets each. West Indies, who had lost their opening encounter against Pakistan, thus have been ousted from the tournament.