Prior, who made an impressive counter-attacking fifty after England lost early wickets in the morning session, admitted that the hosts were not as strong as their Thursday showing in an enticing day of Test cricket.
“It’s number one versus number two in the world. This series certainly isn’t going to go all our way,” he told Sky Sports.
“We had a fantastic day yesterday, not as good a day today but we’re still very much in this Test match.
“We’ve got a good score on the board and it’ll be important to come in tomorrow and put the South Africans under pressure and get a few early wickets.”
South Africa looked like a team transformed in the muggy morning conditions, as Dale Steyn started with a blistering spell, picking up the wickets of overnight centurion Alastair Cook – who added just one to the tally he posted on Thursday – and Ravi Bopara.
Cook misjudged a full one and was bowled for 115, but his Essex team-mate played a half-hearted hook on his return to Test cricket to depart for a duck.
Prior played a typically gutsy counter-attacking knock, scoring 60 before being caught behind by AB de Villiers off the bowling of Morne Morkel – the tall Proteas bowler finished with figures of 4-72.
England’s other recognised batsman Ian Bell departed cheaply for 13, leaving a Jacques Kallis delivery and the hosts finished on 385 all out, having started the day on 267-3.
The afternoon and evening sessions did not survive the south London rain, but the tourists managed to finish on 86-1 at the close of play.
James Anderson removed Alviro Petersen early on with the new ball, trapping the opener lbw for 0, but skipper Graeme Smith (37 no) and Hashim Amla (47 no) – who was dropped by Andrew Strauss at first slip – marshalled the Proteas safely through to the close of play.
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BIOGRAPHY: Hector Bellerin
BIOGRAPHY: Nemanja Matic