Harmison double puts England in control

England's quest to hand Kevin Pietersen his first win as England captain moved several steps closer on the fourth day at The Oval. Steve Harmison bowled a terrific, fiery spell of eight overs, removing South Africa's two key batsmen, Hashim Amla and Jacques Kallis, and was well supported by James Anderson, Stuart Broad and Andrew Flintoff who removed Ashwell Prince 15 minutes before lunch. At the interval, South Africa led by a meagre 46 as England took control.

Unlike yesterday, the conditions were dry and humid - ideal for swing bowling. And also unlike the third morning, Harmison immediately found a probing line outside the off stump. Amla's first shot of the morning was a loose flap to Broad's final delivery of his overnight over, and though the batsman laughed at his frantic stroke, it represented his waning focus on what was a crucial first session for both teams. In the third over of the day, Harmison went wider of the crease and angled in another scorching short delivery that Amla could only fend behind. It was snaffled one-handed with a wobble by Tim Ambrose who lay flat on his back with relief. Outstanding though the catch was, especially considering he has a broken finger, it seems unlikely to be a career-saving one.

It has defied belief to watch Kallis struggle with such consistency this series, and his woes continued on the fourth morning. Harmison was relentlessly fast, forcing Kallis to fend him awkwardly out to point and keeping him well on the back foot. Anderson, meanwhile, initially struggled with his line but soon brought the prodigious swing under control. He couldn't quite perfect his booming inswinger to Kallis, however.

For someone so out of form, Kallis craved a slice of luck - and he got a fat tranche on 9 when he drove Harmison low to Pietersen at mid-off. Yet the very next ball, England ended his series horriblis on 104 runs when he fended a sharp and rising delivery from Harmison low to Paul Collingwood at third slip. South Africa were effectively 16 for 4 and neither Prince or AB de Villiers looked capable of coping with England's disciplined lines.

Pietersen maintained an aggressive, slip-heavy field. And once Anderson had finished his spell, Broad - who has struggled with his bowling in this series - replaced him. He too found booming inswing to Prince, the left-hander, who has lost some confidence since his earlier centuries in the series. Rarely moving his feet, reaching out dangerously for balls wide of his off stump, he drove loosely at a big inswinger from Broad before loosely clattering one out through extra cover.

And all the while, England's best bowler was left relaxing in the slip cordon. After Harmison's superb eight-over spell of 2 for 12, Flintoff was finally brought into the attack and his back-of-a-length pace was not to Prince's liking. An edge fell short of Alastair Cook at point off Broad before Flintoff lured him into a loose cut, the ball flying to Andrew Strauss at slip. To have Flintoff coming into bowl at first or second change is a luxury England have not been afforded for far too long, which only emphasises the influence Harmison has on the whole balance of England's attack. Flintoff grazed de Villiers' visor with a fierce bouncer before shaving his back with another deadly straight one in the next over.

Monty Panesar was brought on for a few pre-lunch overs and found a bit of bounce and turn, but de Villiers fought with impressive resolve to stave him off. Leading by 46, South Africa have it all to do with just five second-innings wickets remaining.