London - They may have arrived in England with a relaxed approach to their Cricket World Cup, but things have gotten serious in a hurry for the Proteas.
Sunday's 21-run loss to Bangladesh at The Oval leaves South Africa with a mountain to climb if they are to make the semi-finals of the tournament, and up next is a clash against India in Southampton on Wednesday.
It is the most daunting of fixtures, especially considering that the Proteas have Lungi Ngidi (hamstring) ruled out while Hashim Amla (head knock) and Dale Steyn (shoulder) as doubts for the match.
More worrying than all of that, though, is how poor the Proteas were on Sunday.
There were moments of encouragement, particularly with the bat, but the South African bowlers were nowhere near good enough as they delivered inconsistent lines and lengths throughout the Bangladesh innings.
The mantra of this side has been to stay calm when results do not go their way in England, but defeat to Bangladesh is likely to bring about a less accepting approach from Du Plessis.
It has, after all, placed South Africa's hopes of lifting a first-ever World Cup title in serious jeopardy.
"From my style of captaincy, there has always been a line, and if you don't perform to that line, then there's a lot of harsh words," a visibly gutted Du Plessis, who made 62 on Sunday, told media.
"I'm certainly not Mr. Nice Guy.
"There are times for strictness and there are times that you see a dressing room needs you to be strong and to motivate them, and that was the case with the previous game when we lost to England the way we did.
"But now, today was not good enough.
"There are absolutely no excuses from me. So if the guys think they can make excuses for a performance like today, then they will be challenged. That's a fact."
The reaction from back home in South Africa following the loss was obviously hostile, with fans clearly angered by the result.
Du Plessis had a message for them, too.
"I think the fans understand that it's not good enough. I'm even going to try to make excuses," he said.
"We are not playing to our full potential.
"What I can tell them is that we will keep fighting."
@LloydBurnard is in England covering the 2019 Cricket World Cup for Sport24 ...