England look to Kevin Pietersen

If England were able to pick the moment the mercurial Pietersen, pictured, returns to his best form, it might easily be in the decisive final Test set to start against South Africa tomorrow.

The stakes could hardly be much higher as England bid to convert a hard-fought 1-0 lead into series victory against hosts who must win and have made no secret of the fact a "result" pitch is being prepared. Should the pace bowlers dominate, as many expect, runs will be the precious commodity.

Pietersen has been short of them by his own high standards, since starting the series with a 40 and 81 in his first Test back after four months out with an Achilles injury.

Collingwood, one of England's saviours in last week's backs-to-the-wall draw in Cape Town, sees Pietersen as a victim of his own success.

Expectations are unfair, he believes – but he nonetheless knows too that Pietersen is capable of meeting them.

"I think sometimes we look at KP and think he should be doing it every single match – and it's probably his own downfall that he's such a good player," said Collingwood. "He's a kind of genius, and when he goes a couple of games without a score people say he's in terrible nick. He can turn it on – and we hope it will be this game."

Collingwood himself can reflect with great satisfaction on his part in England's survival at Newlands – where he made just 40 but defied South Africa for 66 overs on the final day.

He ranks that precious innings – and two more in England's equally unlikely draws at Centurion and Cardiff last year – alongside any of his nine Test hundreds.

"They're right up there," he said. "Last week at Cape Town, we were five down pretty early and backs against the wall – but I always had the belief we could do it.

"It's very hard to measure those kinds of innings, because it's not about runs. It's about the time you spend in the middle, the attitude you show to the other players that we can do it. In many ways I always think they are worth a hundred – but because you haven't got the runs, it doesn't come across that way.

"To get across the line like we have done (so far) in this series, it's a big achievement."

England know they must save their best for last if they are to complete the series victory they crave in South Africa. Their hosts, top of the world rankings little more than a month ago, approach the fourth and final Test at The Wanderers in danger of a shock defeat.

England have already had to do it the hard way to chisel out two astonishing draws at Centurion and Cape Town, number 11 Graham Onions famously twice defying South Africa with nine wickets down in the last over.

An innings victory separated those survival acts to give Andrew Strauss' team an unbeatable 1-0 lead and Collingwood is in no doubt about what to expect tomorrow. "Let's be honest – they're not going to produce a flat, flat wicket," he said. "South Africa are in a position where they need a win – and to do that, they've got to gamble a little bit.

"This wicket does tend to go through a lot more anyway; you get a bit more bounce here. Then if they leave a bit more grass on, it will obviously seam around a bit."