Kevin Pietersen, playing only his second game as the new England captain, and his first One Day game, scored an unbeaten 90 runs to help England to victory over South Africa in the first day-night match of the Series.
England won by 20 runs under the floodlights in Leeds.
Pietersen hails Flintoff's return
By Andrew McKenzie
The BBC
Pietersen and Flintoff (right) helped England set a competitive target
1st One Day International (day-night game), Headingley, Leeds
England: 275-4
South Africa: 255
England win by 20 runs.
England lead Series 1-0
Captain Kevin Pietersen led England to a hard-fought 20-run victory over South Africa in the opening day-night international at Headingley.
Pietersen (90) put on 158 in 21.1 overs with Andrew Flintoff (78 ) as England overcame a slow start to make 275-4.
South Africa began well but Pietersen's off-spin and the recalled Steve Harmison's pace struck back.
Flintoff also took two wickets and the tourists were all out for 255 in a match which went to the final over.
After the disappointment of the recent Test series defeat to South Africa, England will no doubt take great confidence from handing them a first defeat in 10 one-day matches.
Fans enjoying the day-night game under floodlights
Pietersen had earlier promised England would be more aggressive under his leadership and he played a captain's role, not only with the bat but with the ball and in the field.
However, there was little evidence of such positive cricket early on in their innings after he had won the toss and elected to bat.
Ian Bell and Matt Prior got them off to a tentative start as they were happy to play the ball around a slow outfield for ones and twos and protect their wickets, while failing to take advantage of the powerplays.
Prior was the more aggressive but had a let off in the 11th over when he chipped straight down the throat of Vernon Philander, who put down the easiest of chances off the bowling of Andre Nel.
Frustration started to kick in as the England pair went 10 overs without a boundary and the scoring rate dropped below four an over.
Bell tried to up the ante but only succeeded in flashing at a ball from Jacques Kallis and AB de Villiers held on to a spectacular diving catch at backward point.
The opener failed to hit one boundary in his innings of 35 runs from 69 balls.
Prior managed to clear the rope when he got hold of a Kallis delivery to bring the crowd to life.
But he was out for 42 the following ball as he carved a wide one from Kallis straight into the hands of De Villiers.
Owais Shah, who was promoted to bat at three on the suggestion of Pietersen, was joined at the crease by his skipper but failed to stick around.
He holed out in the deep after top-edging a ball from Johan Botha, although Philander initially spilled the catch before gathering at the second attempt.
It brought Flintoff and Pietersen together at the crease, although the latter survived a scare when taking on Philander's arm at fine leg.
Television replays were inconclusive over whether his bat was grounded, but he was given the benefit of the doubt.
After a surprisingly muted start, the pair got going following the arrival of the new ball.
Pietersen's first boundary came after 52 balls when he clubbed a full toss from Botha to the fence.
The skipper passed hit his 19th ODI fifty and was just getting into his stride when he took on a throw from Nel that would have seen a direct hit end his innings.
It was the closes South Africa got to dismissing him and moments later a boundary from Flintoff brought up his half-century and the 100 partnership.
It was the highest fourth-wicket partnership in an ODI against South Africa and the addition of 94 off the last 10 overs was crucial in posting a competitive target.
Flintoff fell in the final over for 78, while Pietersen ended on 90 not out, just short of registering a seventh ton in ODIs.
Harmison and Flintoff proved a potent strike force for England
South Africa's response was helped by some poor England bowling early on, with James Anderson and Stuart Broad proving wayward and expensive.
Harmison was brought on after just seven overs, but a boundary and a wide brought up South Africa's 50.
However, four balls into his return he drew an edge from Smith and Prior held a simple catch behind.
It failed to dent South Africa's progress, however, as Herschelle Gibbs and Kallis kept them comfortably ahead of the required run rate.
Even Flintoff's introduction failed to stem the flow of runs as Kallis dispatched him for three successive boundaries.
Instead it was the introduction of Samit Patel that ended the partnership of Kallis and Gibbs, with the latter clean bowled for 37 as he tried to cut a straight delivery.
But again it failed to stifle the South African onslaught, with Kallis joined by De Villiers.
Pietersen's decision to bring himself into the attack proved inspired as he tempted De Villiers to get out cheaply, chipping straight into the grateful hands of Bell having scored 24.
Bell and Pietersen then combined to run out Kallis on 52 and Prior added to England's victory hopes when he had Mark Boucher stumped off the bowling of the England skipper for 16.
The game appeared delicately poised but helped by some tight bowling from Harmison, the required run-rate edged towards double figures.
Johan Botha looked South Africa's best bet to get across the line, but he was caught by substitute fielder Tim Bresnan on the boundary to give Broad his only wicket.
Philander really struggled to time the ball, and when he was run out for 23 in the penultimate over, the tailenders were left needing 27 off the final over.
Flintoff in got amongst the wickets by bowling Nel and Makhaya Ntini to ensure a victory that - for most of the match - looked in doubt.
The five-match series continues on Tuesday at Trent Bridge.
England pose for a team photo the day before the floodlit match at Headingley - Steve Harmison was added to the squad later
Kevin Pietersen wins the toss and elects to bat first on the day South Africa boycott the Champions Trophy in Pakistan
Ian Bell struggles with the bat, hitting a scratchy 35 off 69 balls before driving Jacques Kallis to backward point
England are 113-3 and in trouble as Pietersen tries to stamp his authority on proceedings, but England continue to score slowly
With Andrew Flintoff for company, Pietersen injects some much overdue acceleration into the England innings
Pietersen has one or two hairy moments but after 40 overs England are up to 181-3 as they set themselves for the final push
In the end, Flintoff and Pietersen both fire, putting on 158 in 21.1 overs as England set South Africa 276 to win
Attention quickly turns to South Africa's chase, and they make a far more positive start with the bat than England managed
But the decision to bring on new face Samit Patel, in the 16th over, brings about an immediate benefit as he bowls Herschelle Gibbs for 37
Jacques Kallis hits an important 50 as South Africa look determined to retain the upper hand and take a 1-0 series lead
However Pietersen takes two wickets, and helps run out Kallis, and suddenly England are on top with South Africa 168-5
Harmison takes 2-43 in a highly effective comeback as England drive home their advantage, and the hosts win by 20 runs
news.bbc.co.uk/sport
England won by 20 runs under the floodlights in Leeds.
Pietersen hails Flintoff's return
By Andrew McKenzie
The BBC
Pietersen and Flintoff (right) helped England set a competitive target
1st One Day International (day-night game), Headingley, Leeds
England: 275-4
South Africa: 255
England win by 20 runs.
England lead Series 1-0
Captain Kevin Pietersen led England to a hard-fought 20-run victory over South Africa in the opening day-night international at Headingley.
Pietersen (90) put on 158 in 21.1 overs with Andrew Flintoff (78 ) as England overcame a slow start to make 275-4.
South Africa began well but Pietersen's off-spin and the recalled Steve Harmison's pace struck back.
Flintoff also took two wickets and the tourists were all out for 255 in a match which went to the final over.
After the disappointment of the recent Test series defeat to South Africa, England will no doubt take great confidence from handing them a first defeat in 10 one-day matches.
Fans enjoying the day-night game under floodlights
Pietersen had earlier promised England would be more aggressive under his leadership and he played a captain's role, not only with the bat but with the ball and in the field.
However, there was little evidence of such positive cricket early on in their innings after he had won the toss and elected to bat.
Ian Bell and Matt Prior got them off to a tentative start as they were happy to play the ball around a slow outfield for ones and twos and protect their wickets, while failing to take advantage of the powerplays.
Prior was the more aggressive but had a let off in the 11th over when he chipped straight down the throat of Vernon Philander, who put down the easiest of chances off the bowling of Andre Nel.
Frustration started to kick in as the England pair went 10 overs without a boundary and the scoring rate dropped below four an over.
Bell tried to up the ante but only succeeded in flashing at a ball from Jacques Kallis and AB de Villiers held on to a spectacular diving catch at backward point.
The opener failed to hit one boundary in his innings of 35 runs from 69 balls.
Prior managed to clear the rope when he got hold of a Kallis delivery to bring the crowd to life.
But he was out for 42 the following ball as he carved a wide one from Kallis straight into the hands of De Villiers.
Owais Shah, who was promoted to bat at three on the suggestion of Pietersen, was joined at the crease by his skipper but failed to stick around.
He holed out in the deep after top-edging a ball from Johan Botha, although Philander initially spilled the catch before gathering at the second attempt.
It brought Flintoff and Pietersen together at the crease, although the latter survived a scare when taking on Philander's arm at fine leg.
Television replays were inconclusive over whether his bat was grounded, but he was given the benefit of the doubt.
After a surprisingly muted start, the pair got going following the arrival of the new ball.
Pietersen's first boundary came after 52 balls when he clubbed a full toss from Botha to the fence.
The skipper passed hit his 19th ODI fifty and was just getting into his stride when he took on a throw from Nel that would have seen a direct hit end his innings.
It was the closes South Africa got to dismissing him and moments later a boundary from Flintoff brought up his half-century and the 100 partnership.
It was the highest fourth-wicket partnership in an ODI against South Africa and the addition of 94 off the last 10 overs was crucial in posting a competitive target.
Flintoff fell in the final over for 78, while Pietersen ended on 90 not out, just short of registering a seventh ton in ODIs.
Harmison and Flintoff proved a potent strike force for England
South Africa's response was helped by some poor England bowling early on, with James Anderson and Stuart Broad proving wayward and expensive.
Harmison was brought on after just seven overs, but a boundary and a wide brought up South Africa's 50.
However, four balls into his return he drew an edge from Smith and Prior held a simple catch behind.
It failed to dent South Africa's progress, however, as Herschelle Gibbs and Kallis kept them comfortably ahead of the required run rate.
Even Flintoff's introduction failed to stem the flow of runs as Kallis dispatched him for three successive boundaries.
Instead it was the introduction of Samit Patel that ended the partnership of Kallis and Gibbs, with the latter clean bowled for 37 as he tried to cut a straight delivery.
But again it failed to stifle the South African onslaught, with Kallis joined by De Villiers.
Pietersen's decision to bring himself into the attack proved inspired as he tempted De Villiers to get out cheaply, chipping straight into the grateful hands of Bell having scored 24.
Bell and Pietersen then combined to run out Kallis on 52 and Prior added to England's victory hopes when he had Mark Boucher stumped off the bowling of the England skipper for 16.
The game appeared delicately poised but helped by some tight bowling from Harmison, the required run-rate edged towards double figures.
Johan Botha looked South Africa's best bet to get across the line, but he was caught by substitute fielder Tim Bresnan on the boundary to give Broad his only wicket.
Philander really struggled to time the ball, and when he was run out for 23 in the penultimate over, the tailenders were left needing 27 off the final over.
Flintoff in got amongst the wickets by bowling Nel and Makhaya Ntini to ensure a victory that - for most of the match - looked in doubt.
The five-match series continues on Tuesday at Trent Bridge.
England pose for a team photo the day before the floodlit match at Headingley - Steve Harmison was added to the squad later
Kevin Pietersen wins the toss and elects to bat first on the day South Africa boycott the Champions Trophy in Pakistan
Ian Bell struggles with the bat, hitting a scratchy 35 off 69 balls before driving Jacques Kallis to backward point
England are 113-3 and in trouble as Pietersen tries to stamp his authority on proceedings, but England continue to score slowly
With Andrew Flintoff for company, Pietersen injects some much overdue acceleration into the England innings
Pietersen has one or two hairy moments but after 40 overs England are up to 181-3 as they set themselves for the final push
In the end, Flintoff and Pietersen both fire, putting on 158 in 21.1 overs as England set South Africa 276 to win
Attention quickly turns to South Africa's chase, and they make a far more positive start with the bat than England managed
But the decision to bring on new face Samit Patel, in the 16th over, brings about an immediate benefit as he bowls Herschelle Gibbs for 37
Jacques Kallis hits an important 50 as South Africa look determined to retain the upper hand and take a 1-0 series lead
However Pietersen takes two wickets, and helps run out Kallis, and suddenly England are on top with South Africa 168-5
Harmison takes 2-43 in a highly effective comeback as England drive home their advantage, and the hosts win by 20 runs
news.bbc.co.uk/sport