The Proteas head into their day-night clash with Afghanistan in Cardiff on Saturday already in must-win territory little more than two weeks after the tournament began.
Opening defeats to England, Bangladesh and India, and a wash-out with the West Indies, have left skipper Du Plessis admitting that South Africa must win their five remaining games to have any prospect of making the semi-finals.
"Week one was a bad start to the tournament but that's done now," Du Plessis said.
"We've got to put all our energy and focus into the now and what's coming up next.
"I truly believe that if we carry those ghosts of the last week with us it's going to be tough to get out of the hole.
"But the conversations in the last couple of days, especially with all the rain around, has given me more time to make sure that the guys are on the right path.
"In an ideal world you would want more practice, but a one net session is not going to make the team play better. I believe it's more (important) the conversations that make sure that we're strong and what we exactly need to do."
South Africa have the perfect opportunity to kick-start their campaign as Afghanistan, who have lost their first three games, are the only side below them in the table.
The Proteas must hope the wet weather which has hit Cardiff this week clears in time, although they might benefit from a kinder afternoon forecast.
Du Plessis said: "We've got to win the five games and that clarity is what we're trying to achieve. To give the guys real purpose in the next five games.
"There was a bit of space for us to make a mistake here or there before, but now everyone has written the team off our backs are against the wall.
"Hopefully that allows the guys to play the way that we can, and I truly believe that if we do that we'll be a very dangerous team.
"We just haven't unlocked the potential that we do have in our side."
Fast bowler Lungi Ngidi could return to the Proteas attack after missing the last two games with a tight hamstring.
Ngidi pulled up after bowling just four overs in The Oval defeat to Bangladesh on June 2, and missed the six-wicket loss to India as well as the West Indies wash-out on Monday.
"He's got to do some work to make sure that he's 100 per cent," Du Plessis said.
"It's a tricky one with fast bowlers as to when they do come back. We're in a position now where we need to win five games out of five so you want your best available for selection.
"But if he's not 100 per cent, or even 90 per cent, in a shortened game with a bit of rain around is it worth the risk?"
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