Quinton de Kock doesn't seem to be the sort of cricketer to over-think things. His batting has a laissez faire air to it, and away from cricket it's the simple things that seem to make him happy. If his social media feeds are anything to go by, he lives an uncomplicated, happy life with his wife Sasha and jack russells Gia and Mia, going fishing as often as possible, adopting the odd nyala antelope and generally kicking back Mzansi-style. On the pitch, he's not enjoyed much success with the bat in cricket's longest format over the last 18 months, but if his form was a concern to him, he hid those worries well.

But still waters run deep, and it may be that de Kock's diffidence is in some way part of an on-field persona: that he, perhaps, thinks and cares more than he sometimes lets on, that his reticence masks a fierce desire to succeed, and that his Test drought has been a concern. His 129 against Pakistan at the Wanderers was de Kock's first century in Test cricket in just over two years, his fourth overall, and his very first in the second innings. When he finally got to the mark, having gone 39 innings without reaching three figures, just for a moment the emotion spilled forth from one of the game's most low-temperature cricketers.

This was a hundred that really meant something, and that with it came a huge sense of relief. The instinctive freedom that has made de Kock so devastating in limited-overs cricket has not translated into Test success - at least, not yet, and certainly not in the last year or so. In 2018, he averaged just 20.41 before Pakistan arrived, but over three Tests he's clicked once again in the longest format.

Cathartic hundreds aren't often easy ones, although the way de Kock cruised through the early exchanges this morning, rifling drive after drive through the arc between point and mid off with a languid, flowing ease and racing to fifty from 49 deliveries, suggested that this three-figure knock was fated. But even a player as laid back as de Kock wobbled just a touch in the nervous 90s.

His favoured cut took him to 98, and a flick through mid-on for a single left him on the brink. Suddenly, a cricketer who has thrived on trusting his instincts in the heat of the moment seemed to be thinking an awful lot about how he might find his next run.

If de Kock seemed a tad nervous, things were no more calm up in the press box, where the situation in the middle evoked memories long buried - 20 years long, in fact - but not forgotten by Shaun Pollock, who compared the atmosphere to that of the Klusener/Donald kerfuffle in the semi-final of the 1999 World Cup.

Certain similarities were in plain view: a left-handed batsman on strike, a fast bowler at the other end, one run needed, and the feeling that there might be an extraordinarily thin margin between glory and disaster.

Facing up to Faheem Ashraf on 99, a touch over two years since he last lifted his lid and raised his bat to all corners in a Test match, de Kock missed out on a full toss, punching it straight to mid-on. Then came a straight drive that would have done the trick, had Kagiso Rabada's right heel not got in the way of it, deflecting the ball to mid-on with de Kock making a rapid turnaround having made it halfway down the track already. While everyone else on the field - Rabada included - could see the lighter side of it all, de Kock looked as if he might burst out of frustration.

He pinged the off side field three more times in the over, surviving a direct hit at the striker's end just to ramp up the tense atmosphere even further before it was all released with another straight drive that this time beat the bowler, the stumps, mid-off and Rabada's boot to bring up the ton. Then there were still waters no more, with all the emotions bubbling to the surface.

He wasn't done there, and now unchained by the burden that indifferent form inevitably places on the shoulders of even the most chilled out cricketers, de Kock cut loose. Clearing his front leg and reverting to the style that has built his formidable limited-overs reputation, he thumped Hasan Ali repeatedly through cover, shrugging off an edge that was dropped by Sarfraz Ahmed behind the stumps with a smile, and then immediately laying into the bowling again. Having set South Africa up with his 102-run stand with Hashim Amla, de Kock pressed home their advantage with a 79-run partnership alongside Rabada, launching his team beyond 300 by smoking a slog sweep onto the grass banks.

This was vintage de Kock, which is perhaps a bit of an odd thing to say about a player who is only 26, but points to the profound impression he has already made on South African cricket. A household name by the age of 21, de Kock is a product of the highveld, and his sharp eye, quick hands and light feet are most suited to the pitches one finds in these parts, which are usually fast and bouncy. The ball flies in Johannesburg, both off the pitch and off the bat.

Over the last two years, de Kock might have struggled to strike the balance between carefree and confident in his Test game, but with a drought-breaking hundred under his belt at the Wanderers, he once again found that most vital element: freedom.