"We cannot choose the game, we cannot choose the rules of the game, we can only choose how we play." From Simon Sinek's The Infinite Game . With intent, if you're Faf du Plessis, who was engrossed in Sinek's book in the South African dressing room for most of the day after facing just six balls in the middle.

Du Plessis arrived at the crease with South Africa on 63 for 3, 436 runs behind, with the very clear task of needing to bat time (an indefinite amount, maybe?) to keep South Africa in the series.

"Finite games are defined as known players, fixed rules, and an agreed-upon objective. An infinite game is defined as known and unknown players, the rules are changeable, and the objective is not to win, the objective is to keep playing the game in perpetuity."

After identifying his team's tentativeness against Dom Bess as a weakness at Newlands, he had the intention to put that right. From the first ball he faced, he was on the front foot, almost toppling over in his enthusiasm to get forward. He shimmied down to cream the third delivery through the covers for four. Then he got a firm stride in and clobbered the fourth through long-off, a shot laced with authority.

Bess, who had up to that point dominated South Africa's top-order, changed his line and went over the wicket. Du Plessis' intent did not change. He went forward again but his attempt to turn the ball around the corner only went as far as Ollie Pope at short leg. Intention unfulfilled. At 71 for 4, still more than 400 runs behind, the finality of the game could be nearing.

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To play an infinite game, according to Sinek, you need five things: A cause, trusting teams, a worthy rival, existential flexibility and the courage to lead. Du Plessis has them all.

His cause has been clear since the day he took over the Test captaincy in August 2016, when AB de Villiers was injured. He would always be the bridge between eras in South African cricket, which has been suspended in transition for most of the last four years. In that time, they've lost all-time greats, like de Villiers, Hashim Amla, Dale Steyn and Morne Morkel and have been through four sets of coaching staff.

While there were times when South Africa looked like a side that had settled - the summer of 2017-18 when they beat India and Australia at home was one of them - there have been many more times when they have been in limbo. None more so than in the build-up to this series. Little more than two weeks before the first Test, Cricket South Africa went through a complete overhaul. No cause in du Plessis' career was greater than seeing his team through these times.

They trusted him to do that, because he has done it before, on the field and off it. His early career feats as a marathon blocker earned him a reputation of reliability but it's his later acts as a leader that du Plessis will be remembered for. In Australia in late 2016, he captained his side to a series win in the midst of a media storm better known as #mintgate, and then scored a century to sign off.

At the failed 2017 Champions Trophy campaign, he was the only player to take responsibility and made captain of the ODI side shortly after and in the home summer that followed, he openly admitted to the team's requests for revenge pitches against India despite what it would do to their own batting confidence. South Africa beat India then and, tails up, went into hosting Australia in a highly-charged clash of sideshows.

Du Plessis was the one who appeared on the Kingsmead changeroom steps to break up the impending blow-up between David Warner and Quinton de Kock which set the tone for a tense series. Du Plessis' captaincy style there was inclusionary - with smooches on his bowler's heads that won hearts - and the right combination of dignified and ruthless. He sympathised with his opposite number, Steve Smith, in the aftermath of #sandpapergate and then made sure his team clinically finished Australia off at the Wanderers. Classy. And credible.

On that occasion, du Plessis was allowed to flourish as a leader because the opposition forced him to. A worthy opposition, as Sinek writes, must be present for the infinite game. England, despite their Test results in 2019 and talk of their inexperienced line-up, are a similar opposition. South Africa have always relished the challenge of playing against them, and frothed at the thought of being able to stick it to the old empire. But to compete with them this time, South Africa needed to make major changes.

That's where the existential flexibility comes in. It's not the same as regular flexibility - to bat in different positions, to change tactics or team composition because of conditions or injuries - it is the acceptance that everything may have to change to advance the cause. In the depths of the CSA crisis, du Plessis kept the heat on the administration by demanding clarity from them and later acknowledged he was willing to experience rock bottom so the entire system could fall apart and be rebuilt. That demonstrated the courage to lead.

Faf du Plessis with his team Getty Images

No-one can doubt du Plessis' determination and willingness. He accepted the Test captaincy at a time of uncertainty, when Amla had stood down but de Villiers had yet to take up his role. He accepted the ODI captaincy when de Villiers stood down having realised it was the one thing he could not do. He kept captaining South Africa when they did away with Russell Domingo, whom he publicly supported, and through back-to-back series defeats to Sri Lanka, a failed 2019 World Cup and the removal of Ottis Gibson, the introduction of a new coaching structure and appointment of a team director which he had not even been consulted over.

He kept captaining when South Africa were whitewashed in India, and when they returned home to an administration on the brink of implosion. Another leader, a less confident, less dutiful one, may have walked away at any of those points but du Plessis didn't because he wanted to see South Africa through.

But soon, it may not be about what he wants. Du Plessis has gone 10 innings without crossing 29 but that is not even close to the worst form among his team-mates. Du Plessis was South Africa's highest run-scorer in 2019 with an average of 41.41 which should still buy him sufficient time in the XI, all things being equal. But they are not.

A schism has been created, mostly on social media, between du Plessis and dropped Test batsman Temba Bavuma, who averaged 19.84 in 2019 and was sent back to domestic cricket to find form after recovering from a hip injury. After scores of 9 and 17, Bavuma brought up his highest first-class score this week, 180, and there is a groundswell of support for him to return to the XI. There is also the consideration of transformation targets, which South Africa will fall even further short of because Kagiso Rabada has been suspended from the Johannesburg Test. He has also been tipped to be a future captain, by assistant coach Enoch Nkwe.

All those things don't mean that a straight swap of Bavuma for du Plessis is going to happen next week - in fact it is unlikely to - but they provide a sense of direction for the future. No matter how much of Sinek's work du Plessis read, he will know that cricket is not an infinite game and that careers end. He has even tried to plot his own path, citing the T20 World Cup as the most obvious exit point. That leaves his Test future uncertain.

The only series South Africa play between the end of this one and the start of next summer is a winter tour to West Indies. Unless du Plessis is considering trying to prolong his career to the home Tests against Sri Lanka and Australia in 2020-21, it is not unreasonable to conclude that the Wanderers Test could be his last. Or at least, his last at home.

Cricket is a finite game and du Plessis' finish is in sight.