Australia cruised into their fourth successive World Cup final, beating South Africa by seven wickets in the second semi-final, in St Lucia, on Wednesday.

The defending champions dismissed South Africa for 149 in 43.5 overs — their lowest World Cup total — and then rattled off the required runs in the 32nd over.

Chasing an unprecedented third straight World Cup triumph, they will take on Sri Lanka in the final on Saturday in Bridgetown, Barbados.

Fast bowlers Shaun Tait and Glenn McGrath, with four wickets for 39 and three for 18 respectively, destroyed the Proteas, for whom Justin Kemp top-scored with an unbeaten 49 from 91 balls.