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 today 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 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 a satisfied 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."

England - who started the series seventh in the rankings and finish it third, just behind South Africa - had time between the downpours at the SWALEC Stadium to bowl just three overs, after putting their opponents in.

Even with such limited opportunity, though, they got rid of the dangerous Herschelle Gibbs cheaply - brilliantly caught behind by Matt Prior off Stuart Broad - in a total of six for one.

The suspicion was then that this match might be about to go the way of the four which preceded it.

Pietersen admitted to mild frustration that weather prevented any chance of the full whitewash - before conceding even he cannot have the weather to order.

"You can't control the rain," he said. "I wanted to get the guys out to make sure we had an opportunity to win 5-0.

"There was a huge incentive for us to win this fixture. It didn't happen. But the guys can enjoy tonight - and to win 4-0 is something we'd have taken two weeks ago."

While Pietersen and Co are intent on further progress in both forms of the game, South Africa's tour has finished on a downer.

Apart from the damp squib in Wales, memories of their famous Test series win have begun to fade as the one-day leg has gone from bad to worse.

Coach Mickey Arthur knows he has much work to do - but is prepared to give Pietersen due credit too.

"He has got results and he seems to have the whole dressing room behind him," Arthur said of the South Africa-born batsman.

"He's brought in a bit of an aggressive style - which has been fantastic. You have to say he has made an impact."

Pietersen's England is a team Arthur admires - particularly the pace and potency of change bowlers Flintoff and Steve Harmison.

"With their key players back fit - Flintoff, that multi-skilled player back - they seem to have a 'brand' that is working for them," he said.

"The one thing we did really well when we were at our peak was the ability to take wickets after the powerplay. They certainly have that ability now, with Flintoff and Harmison.

"That is a huge bonus, because the game gets away from you in the middle overs if you don't have the ability to take wickets.

"They certainly have one of the best one-day bowling attacks around in the world."

Central to that, of course, is Flintoff - and it was an understated post-match delivery from him which provided the last word on a day when the weather gave this newest of venues and its groundstaff headaches aplenty, to little avail.

Cardiff will stage the first Ashes Test next summer and, to many minds, was on trial today to see how it will cope on the big stage.

Manchester, Lancastrian Flintoff's home ground, was one of those which lost out two years ago when the SWALEC was granted not just any Ashes Test but the all-important first of the series.

Asked for his impressions of Cardiff, Flintoff was pithy - and pointed.

"It was damp. It was better than last time I came. It's not Old Trafford - but it's all right," he said.

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