KwaZulu-Natal: Stuart Broad bowled two fiery spells and took three wickets to give England a slight edge at the end of the second day of the first Test against South Africa at Kingsmead on Sunday.
South Africa were 137 for four at the close, still 166 runs behind England`s first innings total of 303.
Broad said England needed to press home their advantage.
"Tomorrow is a big first hour," he said. "We need to make early breakthroughs as South Africa did today and try to get a first innings lead.
"I don`t think anyone really knows how this wicket is going to behave. It`s quite a lot drier than we expected. If it deteriorates a first innings lead could be crucial."
Broad dismissed opener Stiaan van Zyl as well as South Africa`s two key batsmen -- captain Hashim Amla and AB de Villiers -- to finish the day with three for 16 from ten overs.
Opening batsman Dean Elgar withstood the Broad barrage and was unbeaten on 67, although he could have been out for 58 if England had sought a review after an appeal for leg before wicket by Ben Stokes had been turned down.
Off-spinner Moeen Ali took the fourth wicket when he bowled Faf du Plessis.
Fast bowlers Morne Morkel and Dale Steyn finished with four wickets each as England lost six wickets in an extended morning`s play.
Morkel took all of his wickets on Sunday, including a burst of three wickets for no runs off six balls, and finished with four for 76, while Steyn took four for 70.
Morkel`s victims included top scorer Nick Compton, who made a painstaking 85 off 236 balls.
Fresh from making a hard-hit 32 not out in a last wicket stand of 36 with Steven Finn, Broad struck with the second ball of the South African innings when Van Zyl failed to play a shot against a ball which cut back and hit the top of his off stump.
Amla survived two appeals for caught behind off Broad and was dropped by wicketkeeper Jonny Bairstow off Chris Woakes before edging a routine catch to Bairstow after making seven.
South Africa would have been in worse trouble if AB de Villiers, on 11, had not survived an umpires` review after edging Finn low to Ben Stokes at gully.
Stokes was not certain whether the ball had carried, an opinion shared by television umpire Bruce Oxenford after viewing several replays.
De Villiers went on to make an accomplished 49 before Broad came back into the attack and had him caught behind, pushing at a ball which left him off the pitch to provide a second catch for Bairstow.
It was the eighth time Broad had dismissed De Villiers in 11 Tests.
Broad said De Villiers` dismissal was the result of a successful plan, with seven fielders manning the off side.
"AB was starting to take the game away from us slightly. He`s got the ability to hit good balls for four and score very quickly, so we came up with a 7-2 plan, almost to say, you can hit your good shots but you will hit them to fielders." said Broad.
"The leg-cutter moved a bit more than I thought it would but I think encouraging him to play his shots is maybe the way to get players of his calibre out."
The left-handed Elgar, who reached 1000 runs in his 22nd Test when he had 35, went to a 93-ball half-century with a straight six off Ali. He had faced 155 balls by the close, hitting five fours and a six.