South Africa takes 20-run lead as Australia bowlers hit…

Australian captain Steve Smith sets his field

The ICC announced on Monday morning that Rabada, who rattled through the Australian batting line-up and now has six wickets in their second innings, will have to answer a Level 1 offence for his send-off of controversial opener David Warner on Sunday.

Steve Smith departed amid a collapse of 3-24, with South Africa boasting all the momentum after AB de Villiers' sublime century gave them a first-innings advantage of 139 runs.

Rabada took two more wickets, including a crucial late breakthrough to get Usman Khawaja out for 75 seven minutes before the end of the day.

Having made a decision to take a break from the longest format in 2016, only returning in December 2017, de Villiers admitted he was determined to prove that he was still capable of producing match-defining performances in Test cricket.

The veteran required 117 balls to register his 22nd Test century - and his first in more than three years. "So you know you have to get to him quickly and it's important that some of our players get around KG before he gets close to the batsman", De Villiers said on Sunday.

Earlier, Vernon Philander (36) and Maharaj (30) helped De Villiers add 84 for the eighth wicket and 58 for the ninth wicket as South Africa dominated a sunny morning.

He is already facing a disciplinary hearing at this game for bumping into Australia captain Smith after dismissing him in the first innings.

Siddle, who took 46 of his 211 Test wickets against South Africa, said every match he played against the Proteas took place in at atmosphere of high-tension and that he might have even gone "too far" with a send-off.

"I won't say we're frustrated (with him)", he said.

"I think I have probably been in all circumstances, I've gone too far with send-offs, and then other times where you pull it back, you know you have to be controlled", Siddle said on Monday.

Offspinner Nathan Lyon also made his presence felt with the wicket of de Kock for 9.

The incident happened after Rabada scalped Smith's crucial wicket for 25 and celebrated the victory by brushing his shoulder against the departing skipper.

Cricket is a competitive game, and sledging will naturally occur when two sides are going at it, especially when two sides as competitive as Australia and South Africa are involved.

The 22-year-old paceman screamed in delight as he walked in front of Warner, and the ICC have deemed that it could be in breach of their code of conduct. "I have spoken to him a few times about it, to try and get him to relax a bit", Holding told ESPNcricinfo. There was a lot of emotion from that last Test match (in Durban) going into this one and once again as a fast bowler you want to prove things to people, and you want to show everyone you belong on this stage. "I was very nervous in the nineties".

"I think it's up to some of our senior guys to just help him", he said.