The second cricket Test between South Africa and England in Durban is evenly poised.
An Andrew Strauss half century propelled England to 103 for one before bad light ended play early on the second day.
Strauss' 54 came of 67 balls and included nine fours.
South Africa were earlier all out for 343, with the total boosted by a final wicket stand of 56.
Graeme Swann finished with four for 110 in 35 overs to take his year's haul to 49 wickets in 12 tests, second only to Australia's Mitchell Johnson.
The former England captain Michael Vaughn says England are well placed in the match.