South Africa captain Faf du Plessis has challenged his team to save their Cricket World Cup skins by taking ownership of a group-stage crisis.

The 34-year-old said hope alone would get the Proteas nowhere and instructed his slow-starting stars to search within themselves and pull out a string of performances.

Defeats to England, Bangladesh and India - and a rained-off clash with West Indies - have left South Africa in a dire position and with Du Plessis demanding wins from all five of their remaining matches.

On Saturday they face Afghanistan in Cardiff, and another off-day could inflict a fatal blow to their semi-final hopes.

Du Plessis said he has experienced no greater challenge in his tenure as captain, and his man-management skills have been put to an extreme test.

"It's just been checking in with every guy individually ... and then just making sure that I make it clear to them that there needs to be purpose in what's coming up. You can't just hope for things to change," Du Plessis said on Friday.

"Hope's a very dangerous thing for me; you either make it happen [or you don't], the fact that you need to get yourself out of that space as quick as possible.

"And just finding different keys and different players where I feel that they can lead better in different departments, where they can take more responsibility, where they can take more ownership.

"So it's about trying to unlock players' best that is lying somewhere underneath them. Hopefully we can see a little bit of that coming out in the next few games."

South Africa will be hoping for clear skies in Cardiff and to find the display that earns a first victory, with New Zealand, Pakistan, Sri Lanka and Australia their remaining opponents.

"From a challenge, myself as a leader, this has been right up there," Du Plessis said. "But I suppose that's what the last two, three years of captaining this side has prepared me for.

"Whether it's good situations or bad situations, you try to mature as much as you can as a captain to try and be ready for when it's really, really tough because then the team looks to the leaders in the side.

"So it's a hard time, but it's also a time that I'm really owning up to the fact that I need to step up and make sure that I lead the team in a time when they need me."