Kevin Pietersen's England can celebrate their NatWest Series win over South Africa but only on condition they buy into the captain's challenge to continue their self-improvement.

Pietersen's team were yesterday denied their chance to shoot for a 5-0 whitewash and second place in the one-day international rankings by the rain in Cardiff.

They have nonetheless confounded the expectations of many by racking up a 4-0 success on the back of an outstanding man-of-the-series performance from the all-rounder Andrew Flintoff, under the leadership of a man who took over the reins as Test and limited-overs captain less than a month ago.

The uncompromising message from Pietersen, though, is that they will never be allowed to stand still admiring their achievements.

"Playing against a quality side like South Africa in a one-day series you're obviously an underdog, but the way the guys have come out and played and practised has been absolutely exceptional," said Pietersen. "I can't fault anyone for anything. I can't ask for anything more as a captain."

Pietersen is vowing to enjoy the success because tougher days are inevitable, as well as striving to make them continue as long as possible.

"I know there are going to be hard and testing times, especially the trip to India, because it's not easy for any team to tour India," he added, casting his mind forward beyond England's next expedition, for the Stanford Super Series in Antigua, to the trip to the subcontinent which follows.

"I also have a philosophy of really enjoying the good times because when the bad times come along you long for those good times.

"You make sure you enjoy the days like today and this series because it's going to be tough in India and we'll just have to deal with it."

Pietersen is delighted with the reaction of his players since he took charge, but he makes it clear they must carry on giving all they have to the collective cause.

"All the guys are just hungry for success," he said. "There are a lot of players who know they have settled for a comfort zone in certain areas, but I don't live with any comfort zones. I don't settle for mediocrity. I want guys to perform, to chuck their talent around and to be the best people they can possibly be. There's no point living if you don't want to be the best person you can possibly be."

nAustralia crushed Bangladesh by eight wickets in the second one-day international at Darwin to take an unassailable 2-0 lead in their three-game series, writes Julian Linden. The hosts coasted to victory with more than 27 overs to spare after bowling the visitors out for 117 then racing to 118 for two in reply.

Left-hander Shaun Marsh top-scored with an unbeaten 69 while his fellow opener Shane Watson made a brisk 29 as the world champions followed up their 180-run win on Saturday with another lopsided victory.

"We're winning one-day international games for our country, which is the most important thing," said Australia's acting captain, Michael Clarke. "It doesn't matter who you play against, in our team, in our culture, you want to win every game you play."

Wicketkeeper Dhiman Ghosh top scored for Bangladesh with 30 while Mitchell Johnson was the pick of the Australian bowlers after capturing 3-17.

Bangladesh made a terrible start to their innings after winning the toss and electing to bat when Tamim Iqbal was dismissed first ball and two more wickets tumbled inside the first six overs.

The tourists recovered to at least eclipse their embarrassing total of 74 from the weekend but were unable to post a target to seriously challenge the Australians. "We don't see this as an improvement, we are a much better side than this," said Bangladesh captain Mohammad Ashraful.