Andrew Strauss hit his third century of the series to propel England into an encouraging position in the fourth Test at the Wanderers.

Strauss' majestic form has been the feature of the tour to date and his latest contribution provided an ideal start to Michael Vaughan's men's hopes of regaining the lead in the five-match series, which currently stands at 1-1.

The Middlesex opener shared a 182-run second-wicket stand with Robert Key to grab back some of the momentum lost in the heavy defeat to the South Africans in Cape Town last week.

He fell to the third over of the new ball when he sliced to second slip off Shaun Pollock, having struck a career-best 147 during six hours at the crease, as England closed on 263 for four.

Strauss has enjoyed home comforts in his eight months as a Test batsmen, scoring his first two centuries off New Zealand and West Indies at his county base Lord's last summer and this, his fifth three-figure score at Test level, came in the city of his birth.

Raised in a suburb three miles or so from the Wanderers ground, he appeared to enjoy this venue as much.

So prolific has his time been at the top level, in fact, that of those players to have played more than 20 Test innings only all-time greats Sir Donald Bradman and George Headley have a better rate of converting scores into hundreds than Strauss' five in 21.

Such was his dominance, after a testing opening burst from Pollock and Makhaya Ntini, that his biggest moment of discomfort came when Key leg-glanced spinner Nicky Boje and failed to respond to his partner's call. Strauss was more than halfway down the pitch when he turned round to beat Boeta Dippenaar's throw from short fine-leg to the bowler's end with a full-length dive.

That heart-stopping moment, which required adjudication from the television umpire, came five runs short of his century, which arrived from 155 balls and included one towering straight six off Boje and 17 fours.

Key - given an opportunity to lay permanent claim to the number three spot following Mark Butcher's latest injury - appeared as comfortable as his partner after lunch as he imperiously drove the metronomic Pollock down the ground for two of his 11 fours.

His only chance came, on 39, when he drilled a return catch at Boje which resulted in the left-arm spinner needing two stitches in a hand wound.

During the middle session they upped the tempo, Key sweeping a maximum into the grass paddock at deep square-leg and both players attacking youngster Dale Steyn, who claimed the scalp of Marcus Trescothick in the midst of sending down four consecutive maidens at the start of his day's work.

Knocked off his length, however, Steyn - back in the side due to Charl Langeveldt's fractured left hand - proved as expensive as he had in the opening two Tests as 150 runs came in the 40 overs between lunch and Key's dismissal.

As with Trescothick, who provided wicketkeeper Mark Boucher with an early dismissal, Key edged behind the wicket, when a drive at the returning Ntini 17 runs from a second Test century flew to Graeme Smith at second slip.

His indiscretion prevented a repeat of the 291-run share he and Strauss cranked up off the West Indies at Lord's last summer when captain Vaughan shook off a batting malaise to register twin hundreds himself.

Vaughan went into that match having spent a few days under the personal tutelage of coach Duncan Fletcher and he has done the same over the past week in a bid to halt a barren period of 220 runs in 11 completed innings.

The omens appeared good for the England captain when he overturned his poor form at the toss, he had lost 16 of his 22 coin flips in Tests previously, to allow his side first use of a surface which traditionally offers pace and bounce.

But he struggled when he returned to the middle six hours later as South Africa's attack finished strongly as they had begun.

The luckless Pollock breezed past the outside edge on numerous occasions in the final hour although pace partner Ntini did claim Graham Thorpe's wicket -another guide into the slips - shortly before bad light drove the players from the field with more than four overs remaining.

One extra plus point for England, however, is that all-rounder Andrew Flintoff, who came into the game after a fitness test on a side strain, spent the day with his feet up. He has been the tourists' leading wicket-taker so far, although the bowling ranks have been bolstered by the inclusion of James Anderson, whose ability to swing the ball got him the nod ahead of Simon Jones.