On a day that sprung to life after tea and saw 224 runs to go with six wickets, these are the moments that really mattered
Five moments that mattered: Day two
Rabada set to miss remaining Tests
In terms of the wider impact on the series, by far the biggest moment of the day occurred before a ball had even been sent down when it was confirmed Proteas quick Kagiso Rabada had been charged with a Level 2 offence.
The report stemmed from yesterday's fiery response to the crucial wicket of Steve Smith when Rabada brushed past the Australian skipper and made minor contact with his shoulder.
The Proteas quick will contest the charge at a hearing after play on Sunday, where he will try to convince match referee Jeff Crowe that the contact was simply accidental.
A Level 2 offence carries with it 3-4 demerit points, and given Rabada already has five points on his record, the latest indiscretion would see the 22-year-old reach the next suspension threshold (eight points) and cop a two-Test ban to rule him out for the remainder of the series.
Amla's DRS double
Both teams have had their fair share of 'ambitious' reviews already in this series, but Hashim Amla used the system to perfection twice during his half-century on the second day.
Pat Cummins thought he had his second wicket of the morning when umpire S Ravi sent Amla on his way lbw for seven, but the veteran batsman had a quick word with non-striker Dean Elgar and eventually opted for the review.
Watching the initial replay on the big screen, it looked as though Amla thought he was done for, only for the ball-tracker to show the impact of the ball on pad coming outside the line of off-stump to earn a reprieve.
Amla was again given out lbw when on 40, this time off Hazlewood, but immediately sent it upstairs as the replay showed a significant inside edge before hitting pad.
Please don't stop the music
The St. George's Park Band is a staple of cricket in Port Elizabeth, but the umpires finally had enough of the catchy tunes and the one section of the ground that had managed to create something approaching atmosphere when they asked for the music to cease late in the second session.
The band stormed out of the stands as a chorus of boos were directed the way of the on-field match officials.
A chant of 'we want the band' soon broke the silence in a session that saw precisely zero wickets for 43 runs, and it wasn't long before the group made a triumphant return to resume their tunes.
But in scenes bordering on farcical, the umpires refused to allow play to continue until the band had put their instruments down as the officials seemed to suggest the noise was making it difficult to hear nicks down the other end.
The band was more or less muted for the remainder of the day and the atmosphere at the venue was worse for it.
The band leaving, cannot be good for test cricket in PE. They’ve been there for years, supporting their home team. Was great when they got behind us. Every ground and country has their own identity! #peband— mark boucher (@markb46) March 10, 2018
Starc goes off
Australia needed something special after the wicketless second session and, as is so often the case, Mitchell Starc produced a bit of magic to knock over the resilient Amla.
Coming around the wicket with the old ball, Starc knocked Amla's off-stump clean out of the ground to break the 278-ball partnership that added 88 runs to the home side's total.
The key dismissal sparked the tourists' final-session fightback as the Proteas lost five wickets after the tea break to leave the Test hanging in the balance with three days still to play.
Image Id: BD79122FD33F4E05B321C82EF57394D1 Image Caption: Starc knocks over Amla with a seed // GettyLyon roars with de Kock beauty
When AB de Villiers is in the kind of touch where he posts 74no from 81 balls with apparent ease, perhaps the best option is to just focus on knocking over the other blokes around him.
Off-spinner Nathan Lyon did just that when Quinton de Kock – fresh off his knock of 83 in Durban and then a week of unwanted headlines – played down the line as the off-break spun past the outside edge and clipped off stump.
De Kock looked up in total disbelief as the Australians celebrated around him, while Nathan Lyon moved to within six wickets of the magic 300 mark.
Qantas tour of South Africa
South Africa squad: Faf du Plessis (c), Hashim Amla, Temba Bavuma, Quinton de Kock, Theunis de Bruyn, AB de Villiers, Dean Elgar, Heinrich Klaasen, Keshav Maharaj, Aiden Markram, Morne Morkel, Wiaan Mulder, Lungi Ngidi, Vernon Philander, Kagiso Rabada.
Australia squad: Steve Smith (c), David Warner (vc), Cameron Bancroft, Pat Cummins, Peter Handscomb, Josh Hazlewood, Jon Holland, Usman Khawaja, Nathan Lyon, Mitchell Marsh, Shaun Marsh, Tim Paine, Jhye Richardson, Chadd Sayers, Mitchell Starc.
Warm-up match: Australia beat South Africa A by five wickets. Report, highlights
First Test Australia won by 118 runs. Scorecard
Second Test St George's Park, Port Elizabeth, March 9-13. Live coverage
Third Test Newlands, Cape Town, March 22-26. Live coverage
Fourth Test Wanderers, Johannesburg, March 30-April 3. Live coverage