Australia defeated South Africa by eight wickets today in their second Group 2 Super Eights match of the ICC World Twenty20 cricket tournament. In Colombo today, set to score 147 runs for a win, Australia achieved the target by making 147 for two in 17.4 overs. Shane Watson was the top scorer with a fine 70. Earlier, put in to bat, South Africa made 146 for five in the stipulated overs. The final scores: South Africa – 146 for five in 20 oversAustralia – 147 for two in 17.4 overs. With two wins from as many matches, Australia have more or less secured their place in the semi-finals of the tournament.In today's other fixture of the Twenty20 World Cup, India will meet arch rivals Pakistan at the same venue in Colombo at 7.30 P.M.