South Africa face the West Indies in an ICC Champions Trophy match in Cardiff, with the winner set for a place in the semifinals, making the Group B game a virtual quarterfinal.
Both sides have suffered losses to India, while defeating Pakistan, and the scenario in Group B, unlike in Group A, is extremely simple, with India having already qualified for the final four.
Pakistan have already been knocked out of the tournament, with the winner between South Africa and West Indies set to follow India to the semis.
West Indies skipper Dwayne Bravo, whose side were easily beaten by India in their previous match, said the must-win situation against the Proteas made the game on Friday exciting.
"It doesn't make it easier, it makes it more exciting," he said. "That is something we love as players. It's one of the reasons we play the game to become competitive and trust in our skills and our teammates.
"That whenever we're in a position that is a must-win situation, that we all come together and bring our best game. That is all I can ask for from the team.
"We have had a good preparation, and we are looking forward to the challenge again tomorrow (Friday) and hopefully we come out on top."
South Africa were not exactly impressive against India, but found their groove a little bit more against Pakistan, and AB De Villiers said he was not too concerned about possible rain interruptions reducing the game to a shorter one.
"We still rate ourselves as a serious cricket team in whatever format we play and however many overs we play in, anyway," De Villiers said. "I feel we've got a bit of momentum behind us at the moment.
"We play really good cricket, and that intensity I often talk about is really spot on at the moment. Whatever happens tomorrow, rain or not and whichever team we play and however good they are, we'll just go out there and make sure we do the best and play better than them."
South Africa have been given a huge boost, with Dale Steyn, who missed the first two games, expected to be fit against West Indies.
"He bowled at a hundred percent intensity yesterday (Wednesday), and it was sort of the first part of his fitness assessment and today (Thursday) he's doing a bit more," De Villiers added.
"He's 99.9 percent ready, but we're just going to make sure this afternoon that he'll be ready to go. It's almost a yes, just not yet. Just got to wait a few hours and then we'll make the final call this afternoon, but it's looking good."
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