An improved system of adjusting run targets in rain-shortened matches will be introduced this week for the opening one-day international between Pakistan and South Africa in Lahore, the game's world body said on Wednesday.

The new system has been devised to "ensure fairness to both teams in matches where the side batting first sets an exceptionally high total", the International Cricket Council said in a statement.

Under the existing Duckworth-Lewis system, victory targets are revised in rain-affected one-day games. New targets are based on how many overs a side has left to bat and how many wickets have already fallen.

However, this year's World Cup final between Australia and India at The Wanderers in Johannesburg underlined the system's weakness when the side batting first posts a huge total.

Australia, who went on to win the March 23 final by a crushing 125 runs, raced to a record 359 for two in their 50 overs after being unexpectedly asked to bat first by India captain Saurav Ganguly.

India, in reply, were bowled out for 234 in 39.2 overs, but had hopes of snatching an unlikely victory when storm clouds gathered over Johannesburg after they had made a bright start.

"With rain threatening, India, on 145 for 3 after 23 overs, were only four runs behind par," said Frank Duckworth, one of the inventors of the D/L system.

"Losing no more wickets and scoring 12 runs in the next two overs, followed by a terminal downpour, would have handed the title to India.

"We have always been aware that, when the total set by the team batting first is much greater than average, revised targets and par scores can sometimes seem unrealistic," Duckworth added.

The new D/L system will be used for the first time, should rain intervene, in Lahore on Friday when Pakistan host South Africa for the first one-dayer of a five-match series.