England still believe they can win the second Investec Test and level the series against South Africa although those prospects were far from obvious after day two of a contest which is forecast to be interrupted significantly by rain.

Stuart Broad is optimistic that, as long as the hosts can replicate the determination and skill shown by Alviro Petersen (182) in the Proteas' 419, there may still be some room for manoeuvre.

After England had replied with 48 for no wicket in a final session shortened by bad light and then rain, Broad said: "It's pretty even, I think. Being none down for us was vital, and tomorrow the first hour will be huge, because we all have one job, and that's to bat as big and as long as we can."

To that end, Broad will be pinning his hopes on one of England's front-line batsmen repeating the heroics Alastair Cook produced at Edgbaston last year.

There, Cook piled up a career-best 294 against India which first gave England their world No.1 position – a status which is in peril, at 1-0 down with one to play against South Africa.

"We need one of those Edgbaston knocks – 600 – and then put South Africa under pressure on the last day," said Broad, who finished with three for 96. "I think this wicket will eventually get lower, and that's where the four quick bowlers can come into their own: hitting the pitch, and the ball going underground."

Petersen, meanwhile, might not be available to bat again after having gone for a scan on his right hamstring last night.South Africa assistant coach Russell Domingo said: "From what we've heard, it is possibly a grade one tear – which is possibly 10 days or so – but nothing too serious at this stage."