Southampton, United Kingdom: Ben Stokes struck a superb century before pacemen Josh Ball and Mark Wood helped England seal a dramatic and series-clinching two run-win over South Africa in the second one-day international at Southampton on Saturday.

Victory put England 2-0 up with one to play ahead of Monday's finale at Lord's.

Stokes made South Africa pay dearly for dropping him off both first and second balls after the all-rounder had been passed fit to play following a knee injury.

Yet in a match where the Proteas dropped six chances in all, they were still on course for a morale-boosting win ahead of the start of next week's Champions Trophy ODI tournament in England.

South Africa, the world's top-ranked ODI side, needed 20 off the last two overs chasing a target of 331.

That became 10 off 10 balls when David Miller (71 not out) struck Jake Ball for a six and a four off successive deliveries.

But South Africa -- often accused of 'choking' in pressure situations -- saw Miller and Chris Morris (36 not out) fail to score the runs they required as Ball and fast bowler Wood held their nerve.

Wood defended a target of seven off six balls in the last over.

Two singles were followed by a dot ball, a single and another dot ball. 

Suddenly, South Africa needed four off the last ball and Morris could not oblige.

Earlier, Stokes made 101 and Jos Buttler a dashing 65 not out in England's 330 for six after South Africa captain AB de Villiers sent them into bat in overcast, bowler-friendly, conditions.

Stokes, who briefly left the field with a knee injury in England's 72-run win in the series opener at Headingley on Wednesday, showed no discomfort with the bat, although he only bowled three overs.

His 79-ball innings, just his second century in 55 matches at this level, featured 11 fours and three sixes.

Stokes, the Indian Premier League's record two-million-dollar-man, shared stands of 95 with skipper Eoin Morgan, himself dropped twice, and 77 with Buttler.

South Africa's sloppy fielding saw ODI debutant left-arm spinner Keshav Mahraj, who bowled much better than figures of one for 72 in 10 overs suggested, have three catches dropped off his bowling alone.

England were faltering at 80 for three when Stokes came into bat.

The innings then took a decisive turn when Stokes was missed twice in his first two balls, with Maharaj again the unfortunate bowler.

He deceived Stokes with a well-flighted delivery that took the left-hander's outside edge only for the ball to go through Amla's hands at slip for four.

Next ball produced another edge, with wicket-keeper Quinton de Kock failing to hold a more difficult chance.

Stokes subsequently hoisted both medium-pacer Andile Phehlukwayo and Morris high over deep midwicket for sixes.

He had equalled his previous ODI best of 101, against Bangladesh in Dhaka in October, when he found Miller at long-off to give Maharaj a deserved wicket.

Stokes partly returned the favour when he dropped de Kock, then on 28, when he floored a tough one-handed caught and bowled chance with his first ball in the Proteas' innings.

De Kock went on to make 98 and shared a stand of 96 with de Villiers (52).

Amla was hit flush on the helmet grille by Wood before falling falling for 24 when he drove Stokes to Morgan at short extra cover.

De Villiers, who made a sparkling 52 at better than a run-a-ball, gloved a well-directed short delivery from fast bowler Liam Plunkett (three for 64) through to wicket-keeper Buttler.

South Africa then suffered a further setback when de Kock, in sight of a hundred, tried to run off-spinner Mooen Ali down to third man and was caught behind by opposing gloveman Buttler.

De Kock faced 103 balls including 11 fours but the real drama on a now gloriously sunny day was still to come.