Ashwell Prince's second century in consecutive Tests took South Africa past England's modest total as they closed day two of the second Test on 322 for four at Headingley on Saturday.
The tourists, replying to England's 203 all out, led by 119 runs and were beginning to take control of the match when bad light halted play.
Prince, on nine overnight, was 134 not out from 249 balls. He brought his fifty up with a six and reached his hundred with a single five minutes before tea.
AB de Villiers was on 70 from 183 balls and nearing his sixth Test hundred. South Africa lost only one wicket in the day, with Hashim Amla departing in the morning session.
The left-handed Prince, whose innings of 101 was a significant reason why South Africa saved the first Test after following on, rarely looked in danger as he took advantage of the sunny conditions that made batting comfortable.
England were bowled out when the weather was cloudy.
SWEET DRIVE
Prince registered his fifty with a sweetly timed lofted drive straight over bowler Monty Panesar's head for six to prove his growing confidence.
He repeated the stroke soon after to a wider long-on position as the ball sailed even further back into the stands. De Villiers has played an uncharacteristically patient supporting role in the fifth-wicket partnership already worth 179.
Before lunch, England's Darren Pattinson, the swing bowler plucked from relative obscurity by the selectors, claimed his first Test wicket with an lbw from a full toss that cannoned into Amla's pads.
Replays showed the ball may have missed leg stump, though umpire Daryl Harper gave him out after taking his time over the decision.
De Villiers, who was beaten outside off stump first ball by Pattinson, was booed by the capacity crowd as he walked to the crease after claiming a catch on Friday morning that was shown by replays to have been grounded.
Andrew Flintoff, playing his first Test after an 18-month absence due to injury, had economical figures of one for 36 from 21 overs at tea and one for 57 from 28 at the close.
He showed no rustiness and gave little away in a disciplined and sometimes speedy exhibition of pace bowling but got little help from a pitch that became increasingly easier to bat on.
The first Test in the four-match series was drawn at Lord's.
