Behind Faf du Plessis, who was trying to convince David Warner to go back into his own changeroom, Rabada loomed, seemingly ready to get into the argument. But you may not even have noticed South Africa's 12th man Ngidi a few frames before, standing in the passage holding towels for his team-mates, motionless and passive as an angry Warner climbed past him. He was not looking to get involved at all.
When Ngidi was asked if that CCTV footage adequately represented the personalities of both Rabada and himself, he chuckled nervously and said that it probably did.
"When I came out of the changeroom I heard a lot of swearing and shouting, and I didn't know where it was coming from," Ngidi said. "I was just standing there and all the players were coming up, and I didn't know what was going on until I actually saw Warner shouting and screaming. So I was confused - what's going on? Eventually, after everyone was upstairs, then I realised what was going on. I was the passive one in that situation."
And not just in "that situation."
Ngidi regards himself as "a lot more reserved as a person" than Rabada, and it shows on the field. While Rabada snarls and sometimes swears, Ngidi mostly smiles. He delivers balls at the same speed but does not have the same skills - swing and especially reverse-swing - (yet) and he might soon grow tried of comparisons with Rabada. In fact, so might you, but inevitably the discussion comes up.
They're both young and they're both black African, something South African cricket hasn't seen a lot of until recently. Heck, people are still comparing Rabada to Makhaya Ntini, though there are very few similarities between South Africa's first black African cricketer and its new favourite. As the numbers of black African cricketers at national level grow - thanks to targets that have been in place in the domestic system for several seasons - the interest in their backstories and their performance will grow.
So it's worth knowing that Rabada is from an upper middle-class background, with a lawyer for a mother, and a doctor for a father, someone who recognised his son "wanted for nothing." Ngidi is from a lower-income household, his parents are domestic workers and he was able to attend a prestigious school on scholarship. That's where their journeys converge.
Both Rabada and Ngidi were educated at institutions well known for producing elite sportsmen, both were selected to play at the Under-19 World Cup in 2014 - Ngidi never made the trip because of a back injury - and they both made big impacts on the franchise circuit. While Rabada broke Dale Steyn's record for the best first-class haul since the start of the franchise era at the Wanderers, Ngidi took ten wickets at the same ground on comeback from a stress fracture to force his way into the national side.
"I'm starting to find my own feet," Ngidi said. "KG is a great bowler to get information from and to learn from. But I am a different person. I'm a lot more reserved as a person, so I can never say I want to be KG Rabada. I've got my own abilities, my own skills and traits. Having him give me a bit of advice here and there is really helpful. It's helping my improve as a person and as a cricketer."
More noticeably, there's a difference in how Rabada and Ngidi aim to intimidate batsmen, "You can be aggressive within your actions, with what you say, or in general for me, the areas you bowl," Ngidi said, which falls more in line with the attitude South Africa's coach Ottis Gibson wants his bowlers to have. "Things like putting a batsman under pressure, having a presence, letting him know that you're there. Those are the things I lean towards as a cricketer. I don't really have to say much. I feel just a look may be good enough."
But Ngidi had sympathy for Rabada, whose reactions after dismissing Steven Smith and David Warner in the second Test - with a yell, a shoulder brush and a send-off - earned him four demerit points in total, a 65% fine of his match fee, and a suspension from the rest of the series.
"Everything happens in the moment. You don't have any control over emotions. You try and control them as much as possible but the game means so much to us as players, that you can't really hold yourself back if you are excited or happy," Ngidi said. "He is an aggressive cricketer, that's just the way he plays. I am a different type of person. So it may look different but that's the way we play."
Rabada's suspension means Ngidi is likely to play the rest of the series, after missing the first Test and being brought in for Morne Morkel in the second. In only his second Test, Ngidi took five wickets and displayed impressive control, especially in Australia's second innings where he was the most economical seamer and conceded at 1.84 runs an over. His maturity is a stand-out element of his game, more so because he recognised he could become overawed.
"You see how fast Mitchell Starc bowls on TV and you're in awe of someone who can deliver a ball at that speed. But when you're out there you've got a job to do. You put all those things aside and you focus on what you have to do at the time," Ngidi said. "So there's no point being scared. You're going to have to go out there and bowl to Steven Smith, who's the best in the world. I've also been selected for the team and for the country. So that probably plays a bigger role in my head than who I'm playing against."
While almost everyone else in the South African changeroom talks up Australia as their fiercest rival, Ngidi downplayed the tension. "I found them to be challenging at times but we are just as good a team and we've put them under pressure as well," he said. "They are a competitive team but they are not impossible to beat."
Seldom have South Africa had someone who can call a situation so simply and, luckily for them, Ngidi should be around to do it for a long time. During the Test, Ngidi was also awarded his first national contract. "I didn't expect the national contract but I will take it in my stride as well. I'm just really enjoying everything that's happening. The pace might be quick but taking it a day at a time."
In just 10 months, Ngidi has gone from withdrawing from the A tour of England to return home to remodel his lifestyle and work on his skills, to national selection, to an IPL deal, and now to a central contract. And from that list, there's not so much that's different about him and Rabada after all.