Runs at a premium in England-South Africa Test decider

South Africa's Keegan Petersen has no doubt first-innings runs hold the key to the outcome of the third and deciding Test against England at The Oval starting Thursday.

The Proteas won the first Test by an innings and 12 runs at Lord's only for England to level the three-match contest at 1-1 with an even more emphatic innings and 85-run victory at Old Trafford, with both games finished inside three days.

The second Test saw Ben Stokes make his first hundred as England captain, with wicketkeeper Ben Foakes reaching three figures as well for the home side.

South Africa have managed just one individual fifty so far this series - opener Sarel Erwee's 73 at Lord's.

The Proteas have a fine pace attack featuring Kagiso Rabada and express quick Anrich Nortje, which has helped propel them to four undefeated series prior to this campaign, but have decisions to make over their batting line-up.

Batsman Rassie van der Dussen has already been ruled out of the finale with a finger injury.

With Aiden Markram averaging a mere 15.56 in his last nine Tests, there could be a double alteration to the batting line-up, with both Ryan Rickelton and Khaya Zondo in line to be recalled.

'Step up'

Petersen made a gutsy 42 in South Africa's second innings at Old Trafford but knows such scores rarely win matches.

"I think it is obvious we need to score hundreds up top," Petersen, still awaiting his first Test century after nine matches, told reporters on Tuesday.

"It hasn't been there for a while and the lower order has saved us a few times but I think it is evident the batsmen need to step up and get a couple of big scores.

"I think both Test matches (in this series) were lost in the first innings when it comes to batting... the team who can play that first