South Africa have a reputation of underperforming in big tournaments, which the skipper put down to the players stressing over doing something special.
"In previous World Cups, we wanted to do Superman things. We thought we had to be more special, we had to do something more than we usually do, and we did not do what was good enough before," he told reporters on the eve of the team's departure for England. "We haven’t always got that right in the past, to play our best cricket at the World Cup, because we put so much pressure on ourselves. We want to just focus on enjoying our cricket."
Du Plessis said the key would be for the players to overcome the fear of failure and hoped that he could draw on his own experiences to help them cope with pressure.
"We started a year or two ago with a real focus on mental preparation and, as a captain, I probably speak more about that than previous captains," he said. "But I really believe it’s an area we can get better in. I’ve been there and I know the pressures, I understand how to deal with them.
"There’s a reason why we want the guys to play freely – because we don’t want them to have a fear of failure, which is what the World Cup is for some of them. Our success in England over the next couple of months depends on how well we release that aspect of our play – we need that for the team to be at our best. Each player needs to find out his own strengths."
The 34-year-old also wouldn't commit to Hashim Amla making South Africa's starting XI and said that selection would come down to the form of the players. Amla's form has been a matter of concern lately. He also hasn't played much cricket for South Africa recently, owing to his father's critical illness.
"In terms of team selection, that's a call we will make when we get to that first game," du Plessis said. "We have two warm-up games. Generally, we want to pick on form. If we believe Hash [Amla] is the guy with the best form for the first game, then he will be picked. But if we feel there are other guys that are more in form [we will pick them].