Australia's Andrew Symonds took his World Cup average to 163 on Tuesday after scoring 91 not out against Sri Lanka in their World Cup semi-final on Tuesday.

Symonds, already at the top of the tournament averages before Tuesday, made almost half of his side's runs off 118 deliveries, with seven fours and one six, as Australia ended on 212 for seven after opting to bat first on a slow pitch.

The big-hitting 27-year-old came to the World Cup as something of an underachiever, having made just two half centuries in 54 one-dayers at 23.81 runs a visit.

But his fortunes changed with a match-winning maiden century of 143 not out off 125 balls against Pakistan at The Wanderers in Australia's opening Group A match.

He has scored 326 runs in five innings but has only been dismissed twice.

Bowler Andy Bichel, who made 19 not out alongside Symonds on Tuesday, took his tournament average to 117, having been dismissed just once in three visits to the crease.

Ramnaresh Sarwan of the West Indies has the next highest batting average of 104.5, while India's Sachin Tendulkar, the highest run-scorer at the World Cup with a record 586, is averaging 65.11.