Quinton de Kock does not immediately come across as a leader or a deep thinker or anything other than incredibly instinctive. However, it is that natural cricketing nous that has seen him elevated to South Africa's stand-in captain for the remaining two ODIs against Sri Lanka.

Broadly speaking, with the series already won and the opposition barely proving a challenge, it should not matter much who captains South Africa but it is significant that de Kock was chosen above other candidates in the current squad. It is, perhaps, a peep into the post-2019 World Cup future.

If all South Africa wanted was to go through the motions, they could have asked former captain Hashim Amla to step in. Though Amla's reluctance to lead is well-documented, it's unlikely he would have said no to filling in as an emergency replacement and his seniority would have ensured a smooth transition.

If the next two matches are nothing more than a formality, JP Duminy, who will captain in the lone T20, could have taken over. Duminy has captained at both franchise and at international level before, and is finally batting like a man in charge, so he would have been a welcome choice. And if South Africa wanted to do something different and give a future leader the chance to get some experience in the role, they could have gone back to Aiden Markram, who took over when du Plessis was injured against India. But Markram's white-ball game has gone backwards since the 1-5 defeat to the extent that he was dropped from the third ODI, and so the succession plan may not be as clear cut as it seemed. De Kock, therefore, has a real opportunity over the next five days; an opportunity to show he could be next.

"Aiden captained against India and he is not currently in the team, he has had some struggles on this Sri Lanka tour so far. We thought we would have a look at Quinton for the next two games, which will give Aiden time to settle himself," Ottis Gibson, South Africa's coach, said. "He is a fine player and we are confident he will find form and there will be other opportunities for us to continue to grow that side of his leadership."

Markram may still be the long-term choice but de Kock could be on trial to take over if du Plessis does indeed use the 2019 World Cup as a swansong, which he has suggested in the past, and there is evidence to suggest de Kock is not a bad choice. Scant evidence, but evidence nonetheless.

De Kock's only previous captaincy experience came more than six years ago when he captained the South African Under-19 team in a triangular series involving Zimbabwe and Pakistan in 2012. De Kock was in charge for nine games, of which South Africa won five and lost four. Importantly, de Kock scored three hundreds in that series. More recent evidence came last Sunday, when de Kock took over after du Plessis left the field in the 10th over of the Sri Lankan innings.

At that stage, Sri Lanka were 73 for 3, scoring at 7.30 to the over, just above their requirement of 7.28. Although the sense was that South Africa only needed a wicket or two to swing the advantage their way, the situation still needed careful management. Two overs later, de Kock provided that when he decided to review a catch down the leg side off a Wiaan Mulder slower ball. Umpire Nigel Llong decided it was not out but de Kock was convinced otherwise and replays proved him right. Thisara Perera was out and with him, a significant chance of Sri Lanka staying in the series.

In the 42nd over, when Dhananjaya de Silva was threatening an unlikely coup, de Kock reviewed again when an Andile Phehlukwayo ball appeared to go under de Silva's bat. Llong said no again but replays showed a thick under edge, ending Sri Lanka's challenge.

While those are two small examples, they prove de Kock knows more than he sometimes lets on. "I have always found Quinton to have a good cricket brain, he understands the game," Gibson said. "With Faf [du Plessis] injured, it seems like a good opportunity and chance for him to show that side of his game as a leader for the next two games. He is someone who understands the game, he is constantly helping the captain on the field, he shows good leadership on the field even as a normal player."

In typical de Kock fashion, the man himself expressed some reticence over the magnitude of the role. "To be honest, I am feeling quite nervous," de Kock said. "It is an honour to be given this responsibility of captaining the Proteas. I want to carry on where Faf has left off and to continue with his legacy. As a captain, I will try to stay true to myself and stay true to what I believe it takes to be a good leader. I will strive to help others going forward, just to be there as a captain."

De Kock's task will be a little harder than du Plessis', and not just because he is new to the job. South Africa are committed to experimentation in the last two matches which could see them bench their most experienced seamer, Kagiso Rabada, and include some younger batsmen. But that also means the outcomes will not be used to judge de Kock completely and so, he will have a certain freedom for the next few days, which is exactly what he most enjoys.