Harare - Zimbabwe must pull off a second shock victory in the space of five days on Thursday but must also beat South Africa by a big enough margin to qualify for a one-day triangular series final against Australia.
The hosts stunned the cricket world on Sunday when they beat Australia, who were the No. 1-ranked ODI team at the time, for the first time in 31 years.
The result gave Zimbabwe a glimmer of hope that they could reach Saturday's final, but their chances grew even slimmer when Australia beat South Africa by 62 runs on Tuesday to clinch their spot in the final.
That left Zimbabwe needing not only a bonus point win over South Africa on Thursday, but also to significantly improve their inferior net run rate if they are to qualify at the Proteas' expense.
"We have to play out of or skins again and do the processes right," captain Elton Chigumbura said.
"If we do that and play our best cricket then you never know what can happen, it's a game of cricket."
While Malcolm Waller had been due to leave the Zimbabwe squad for a six-a-side tournament in South Africa on Tuesday, his departure has been delayed after he played a useful role in Sunday's victory.
Waller added six overs of spin that prolonged Australia's difficulties with the bat and then saw off Nathan Lyon during his innings, which set the platform for Chigumbura and Prosper Utseya's heroic partnership in the three-wicket win.
Zimbabwe's task will be made even harder by South Africa's decision to play a full-strength side on Thursday.
Given that the Proteas have a net run rate of 0.118 and Zimbabwe's is -1,665, it had been thought that the tourists may rest some players.
"I don't see it like that. We feel that Zimbabwe is a threat now," Faf du Plessis said.
"They play well in these conditions and they prepare wickets that suit then.
"We expect a slow-turner in the next match. We need to beat them now. I don't think it's time to rest players."
South Africa's main concerns following their defeat to Australia is over their end of innings bowling and their middle order.
Although the Proteas reduced Australia to 188 for five after 42 overs on Tuesday, Mitchell Marsh hammered seven sixes to see Australia to a total of 282 for seven.
Then, after the prolific trio of Hashim Amla, Quinton de Kock and AB de Villiers had fallen cheaply, the middle order was incapable of swinging the game back in their favour.
"I think the way the wickets play here is definitely a big reason for that," said Du Plessis.
"The ball gets a little slower so it's harder to score when you come in as a new batter because they bring the field up and it's quite tricky to get singles."
Zimbabwe: Elton Chigumbura (captain), Sikandar Raza Butt, Tendai Chatara, Luke Jongwe, Tafadzwa Kamungozi, Neville Madziva, Timycen Maruma, Hamilton Masakadza, Shingirai Masakadza, Tinotenda Mawoyo, Natsai M'shangwe, Cuthbert Musoko, John Nyumbu, Vusimuzi Sibanda, Brendan Taylor (wk), Donald Tiripano, Prosper Utseya, Brian Vitori, Malcolm Waller, Sean Williams.
South Africa: AB de Villiers (captain), Hashim Amla, Kyle Abbott, Quinton de Kock (wk), JP Duminy, Faf du Plessis, Imran Tahir, Ryan McLaren, David Miller, Morne Morkel, Wayne Parnell, Aaron Phangiso, Rilee Rossouw, Mthokozisi Shezi, Dale Steyn.