His team was 45 for 4 in pursuit of a gargantuan target of 430 with more than a day to play. He had already scored a first innings 78. He was on debut. He had nothing to prove.
Now, his team has won the series 2-0. He has not contributed much with the bat but has made up for it in the way he has taken control. He is the captain. He has everything to prove.
Faf du Plessis' Adelaide adventures are crucial markers in a career that was made in Australia. This is where he earned respect four years ago, it is where he has lost some after being found guilty of ball-tampering, and it is where he has the chance to regain it.
If South Africa win the day-night Test, du Plessis will become the only man to lead a team to a 5-0 ODI series whitewash over Australia and a 3-0 Test series win over them. Even if he never leads South Africa again, those feats alone would see him named among their most successful captains. And one of their best supported.
That du Plessis has the change room is obvious. They have formed a laager around him quicker than ants congregate on spilled sugar, and that was before they even knew there was a chance he would be charged.
That du Plessis has the wider cricket community behind him is also becoming apparent. Former players, including Australian ones, have condoned his method of shining the ball. "It's also been pretty cool to see that 99.9% of the cricketing world has supported me," du Plessis said.
Even when he makes a comment like that - one that could easily read as arrogant - he comes across human. He always has.
When he debuted in November 2012, he was known as the guy who choked in the chase of the 2011 World Cup quarter-final, someone who is easily ruffled. When he blocked out an entire day to draw the Test in Adelaide four years ago, he became a hero, someone with character. When he blatantly used saliva that had come into contact with a mint to shine the ball in Hobart, he was branded a cheat, someone to be vilified. When he was kept away from reporters at Adelaide airport, who were eventually on the receiving end of heavy-handed bodyguarding from South Africa's security officer, he was deemed pampered, someone with too much swagger for his own good.
Through all of that, du Plessis was on the front and back pages, on the television news and on the radio, and he has taken it in his stride. "Thanks for the love the last week. I never thought that I am that famous that I can make the headlines every day. That was a pretty cool experience," he told the 50-plus reporters who had gathered for his pre-match press conference.
After he made them laugh, he turned completely serious and explained why he had not made any comment on the allegations against him until today. "It's not like I was disrespecting the media by not answering questions. I was not allowed to speak," he said. "What happened at the airport was pretty disappointing to see how things unfolded. I was never really going to be able to give any answers."
Du Plessis' spectrum of answers is what makes him one of the most engaging cricketers on the current circuit. He is quick on the one-liners - "I'll be sleeping with him tonight," he said about Kagiso Rabada after Perth, and "It's his turn" was his quip for Kyle Abbott post Hobart - but careful when dealing with more meaty material. On this tour alone he has explained the cultural shift in the South African camp, tactfully distanced himself from former captain Graeme Smith's scathing criticism of the Australian set-up, been open about his desire to continue captaining but mindful that his best friend actually has first dibs on the job, and stuck to his guns despite being found guilty and fined his entire match fee.
None of that makes him perfect. Du Plessis has contributed a top-score of 37 in the series, and though it was an important 37 in a first innings that needed steadying, he will expect more from himself, especially because despite everything, his place may not be entirely safe. It was only ten months ago that du Plessis was dropped after scoring just one century in 12 innings. When AB de Villiers returns, du Plessis and JP Duminy could find themselves in a shootout for a spot.
Adelaide Oval was where du Plessis showed he could bat - bat big and bat brilliantly. He knows that it is where he needs to show it again. His career could be defined by it, as it was four years ago.
Then, no one expected him to play such a telling role in the series, not even his girlfriend. He was the reserve batsman on the tour, given an opportunity through an injury to Duminy. By the time du Plessis knew he would be playing, she had already booked a trip to visit her brother in Melbourne. She did not see his innings, but a year later she became his wife. Today is their third wedding anniversary. At least to one person, he has already proved it all. Now he has to prove it to the rest.

Firdose Moonda is ESPNcricinfo's South Africa correspondent