Mitchell Johnson says the continuing presence of the world's top-ranked batsman, A.B. de Villiers, at the crease would ensure Australia did not get carried away from having South Africa stricken at 6-140, still 58 runs from denying Australia the opportunity to enforce the follow-on.
Johnson continued his stellar Ashes form by tearing through the Proteas' batting order with the new ball on day two of the first Test, taking three wickets within his first four overs.
The home team will resume at Centurion Park on Friday with de Villiers on 52 and Robin Peterson on 10, with a task of significantly reducing the gap to Australia's first-innings total of 397 before its bowlers are called to the crease.
In reaching his half-century milestone shortly before stumps de Villiers, the Proteas' vice-captain, made it 11 consecutive Tests in which he had done so. That not only extended his lead among wicketkeepers - the next best is five - but lifted him level with the West Indies' Viv Richards and Indian openers Gautam Gambhir and Virender Sehwag as the only batsmen in Test history to achieve that feat.
The over after reaching his milestone de Villiers required medical treatment after being struck on the forearm by another hostile Johnson delivery, although his coach Russell Domingo later said it had not resulted in injury.
Johnson, who finished the day with 4-51 after claiming the late wicket of Ryan McLaren, rebuffed questions about whether Australia would enforce the follow-on and force South Africa to bat again immediately if it dismissed it before it reached 198.
"We've still got four wickets left, A.B. de Villiers is still in. We've still got a long way to go," he said.
"We know (Robin) Peterson can score runs as well. Their tail can score runs as well, they've done it to us in the past.
"We really need to focus on getting ourselves right and bowling well tomorrow morning, because we don't want them to get away from us."
Johnson's new-ball spell of 3-10 snared him the wickets of South African captain Graeme Smith as well as Alviro Petersen and Faf du Plessis. While Petersen fell to a meek waft outside off-stump Smith and du Plessis were both the victims of vicious short-pitch deliveries.
Johnson said the tactic of bowling short came from a combination of noticing while he was batting that rival bowlers Morne Morkel and Ryan McLaren were getting steep bounce from one end when they bowled around the wicket - Johnson's customary over-the-wicket line - and also because he doubted he would be able to swing the ball given the weather and pitch conditions.
"I'm just trying to hit the wicket as hard as I can. I didn't feel like the ball was swinging, so my plan was to bang the wicket hard - and it came off," he said.
"I just felt like there was something going on with that wicket. It was a little bit like Durban a few years ago [in 2009] where it was just really skipping off."
Johnson said he had been particularly pleased to have claimed the scalp of Smith - a batsmen he has injured twice in the past - with a bouncer that forced him to take his eye off it, after which it lobbed high off his bat for Shaun Marsh to take a well-judged catch in the slips cordon.
"It's nice when a plan like that comes off," he said. "When I got here [South Africa] it definitely is in the back of his mind what's happened previously, but he's done so well for his country and you just never know."
He was also rapt to have du Plessis fending to Australia captain Michael Clarke at second slip, from a delivery that reared more than he expected it to.
"If I can keep producing balls like that I'll be pretty happy," he said.
Despite express-pace and bounce playing a part in all four of Johnson's wickets the left-armer rejected the suggest the Proteas batsmen were scared when facing him.
"We are playing against the world's number-one Test team, I don't think there was fear. Maybe a little bit surprised at the wicket but I wouldn't say it's fear," he said.
"We just played against England and that was question was raised. There was other people saying that there was fear in eyes but they are professional sportsmen. They've faced Morne Morkel who gets extreme bounce and pace, so there's no fear.
"Being a left-armer with the different angle I get to the right-armer [is harder for them to adjust to], and I'm probably using my short ball more than I have in the past and it's probably a bit better directed as well, so I'm probably making them play a bit more."
Proteas coach Domingo cited Johnson's angle as a left-armer and trait of having a less upright action than many of his peers as factors in why his batsmen struggled to face the Australian, who he declared was "on a hot streak".
"The challenge is always going to be with his action knowing which balls to leave and which ones not to leave in terms of the length because he can be quite skiddy and that's why he's so dangerous," Domingo said.
"A guy like Morne obviously gets bounce but it's probably a bit more consistent because of the high arm action whereas he is a little bit more inconsistent with the amount of bounce he gets and that's the challenge. That's what we expected. He's an X-factor bowler for Australia and has done really well for a long time. He's done really well in South Africa on previous tours and he's just come off a hard Ashes series so he's got a lot of confidence."
Johnson said it had been easier for him to bowl aggressively upfront because of the performances of Shaun Marsh (148) and Steve Smith (100), who shared a 233-run partnership across days one and two.
"The game has been set up with the way the boys batted early on. Shaun Marsh, the way he batted was sensational, and Steve Smith as well. To have those guys do what they did yesterday and this morning, it definitely gives us bowlers a lot of confidence and gets us into a rhythm pretty early," he said.