Hashim Amla and Graeme Smith both scored centuries to put South Africa firmly in control of the First Test at The Oval.
Graeme Smith was the first to reach three figures, when he cut Tim Brsenen for four just before lunch.
They continued to pile on the runs after the lunch break, this time Amla celebrating his century.
Tim Bresnan finally made the breakthrough when he bowled Smith for 130.
That brought Jacque Kallis to the wicket, who wasted no time and cashed in on a flat pitch, bringing up his 50 off 94 balls.
It was Hashim Amla's day though. South Africa's number three went past 150 and eventually finished on 183 not out.
The visitors ended on 403-2, giving them a first innings lead of 18 runs and opportunity to build a big lead on Sunday.
Speaking after the day's play South African captain Graeme Smith said: "It was an outstanding day. We knew we had to
make a few plays and we've done that.
"Now there are two big days left in the Test match."