Glenn McGrath has issued a subtle warning to the opposing batsmen, saying his immaculate spell of fast bowling in Australia's opening World Cup game against Scotland on Wednesday was nowhere near his best.

"It could have been better, but I will take it. We are still getting used to the wickets, Hopefully I can improve on it," McGrath said after returning 3-14 from six overs.

The three-time champions posted a 203-run win against Scotland at Warner Park, the second biggest margin of victory in World Cup history.

Captain Ricky Ponting was the man of the match with a vintage 113 off only 93 balls that tied him with former teammate Mark Waugh and India's Sachin Tendulkar and Sourav Ganguly for a record four centuries at the World Cup.

Ponting said despite McGrath's sublime show, the work of slow bowlers Brad Hogg and Brad Hodge was a sign of things to come in the tournament.

"Wickets later on in the tournament will turn more probably. Hodge was a huge positive for us," he said.

"Michael Clarke can do it as well."

Losing skipper Craig Wright said Scotland lost the match in the final overs of the Australian innings and with the bat.

"The last five overs of theirs and first 10 of ours killed us," he said.

"It was a small ground and we did pretty well for 45 overs. We were good in the field but our batting didn't start well."