When Dale Steyn shows signs of irritability, the opposition should start worrying. The last time Steyn looked really angry, he returned from an ordinary day in the field to take two wickets in two overs and spark an England collapse that later proved to be series-defining.
In Perth, he will turn up after "two Tests where I have not done too well," and the bristle has begun. "Why would I want to come to Australia and be below average or average? You always want to come here and take five-fors," Steyn said. "Just like as a batter you want to come here and score hundreds under immense pressure against one of the best teams in one of the most difficult places to tour in the world. Hopefully I can have a fantastic game in this one."
On average, Steyn has taken just under five wickets a Test in the 59 he has played. In Brisbane, he claimed only one of the five the South African attack managed in total. In Adelaide, he got closer with four scalps and thought he bowled a lot better. Although there was no swing, Steyn had better control and a touch more pace but he stopped short of spitting fire.
The smouldering mood he was in at the SCG late on the last day of the tour match has yet to ignite, though. There, he sent down one of his fastest spells in Jacques Rudolph's recent memory and it may take a real pressure-cooker of a situation before he explodes again.
Something like Perth. Being the Test that will decide the series, Australia coach Mickey Arthur expects that Steyn will be readying for the big occasion and the man himself confirmed that. "There is a bit more want, a bit more need and that extra push. I know I will probably have a couple days off after this and I will do everything I can to get a result and to get the wickets South Africa need in this match."
But he won't be able to do it alone. Steyn emphasised the rest of the attack will have to keep adding to the incremental progress they made from Brisbane to Adelaide so that they bring the full package to Perth. "It's going to take everything out of everyone to win it," he said.
Although it is Steyn who has become Graeme Smith's go-to man, in the same way Peter Siddle is Michael Clarke's, he maintains he is not the only one with the tools to do the job. His reputation, according to him, was built only on been given the opportunity to dust off the tool box more than most and knowing how to use them well. "I don't think I am the best bowler in the world and I am not the most skilful," he said. "I am just fortunate enough to play every game for South Africa, I bowl a lot of overs for South Africa and I am able to take wickets when we need them.
"Hopefully I can take wickets in this game. That's what I am employed to do and that's what I love doing. It comes down to one last game and it's going to be a team contribution to winning this series. It's not going to be just me standing up and taking seven or five wickets. Morne Morkel took eight in the last game. We will need a massive contribution from all of our bowlers."
One of the regular members of the attack who will not be able to contribute in any way is Jacques Kallis. While the physiotherapist is racing against the clock to get Kallis fit to bat, he has been ruled out from bowling in Perth and will leave a significant gap. "He is massive for us," Steyn said. "Everyone can see he has been batting really well. But he can also hold up an end, he can take wickets, he is a valuable asset to this unit. An injury likes this puts a massive emphasis on what a great cricketer he really is and what a massive contribution he makes to the side. If he just misses one game, it's massive but the day he retires, it's going to be a whole different story."
Even without him, South Africa showed some glimpses of the attack that are known as the best in the world. "When we picked up the last five wickets in Adelaide for not many runs is pretty much how I know this attack can bowl and hopefully if we can string it together properly here in Perth, which is just around the corner for us, we could go home 1-nil."
With that in mind, Steyn extended his bullishness to the whole team. South Africa need only a draw to keep their Test mace but Steyn warned that they are still aiming for the Australian jugular. "We want to win the series. We didn't come down to Australia to draw. We've played below what we are capable of but Australia have thrown everything they can at us and they still haven't beaten us. If we can play to what our potential is, I think we will go home 1-nil."

Firdose Moonda is ESPNcricinfo's South Africa correspondent