Johannesburg - England stretched their lead beyond 300 after deciding not to enforce the follow-on on the third day of the fourth and final Test against South Africa at the Wanderers Stadium on Sunday.
Dom Sibley was unbeaten on 39 as England batted cautiously to reach 86 for two in their second innings at tea, an overall lead of 303.
Earlier, fast bowler Mark Wood took five for 46 when South Africa were bowled out for 183 in their first innings, a deficit of 217 runs.
Quinton de Kock (76) and Dwaine Pretorius (37) kept England in the field for most of the morning and probably made sure England would decide to bat again. They put on 79 for the eighth wicket and prevented England from wrapping up the innings early.
Vernon Philander was out to the sixth ball of the day, reducing South Africa to 93 for seven, at which stage a follow-on seemed a strong possibility.
It was an unhappy day for Philander, who will be retiring from international cricket at the end of the match.
Apart from his early dismissal for four, he received a fine of 15 percent of his match fee for his 'send-off' of Jos Buttler on the second day - and he pulled up with a hamstring injury after bowling just nine balls in the second innings. He left the field immediately and was sent for a scan.
De Kock scored his fourth half-century of what has been a poor series for the South African batsmen. His team-mates have contributed only five other 50-plus scores between them.