England coach Ashley Giles has issued a strong denial that England unfairly altered the condition of the ball, in search of reverse-swing - a claim made by former Test captain Bob Willis, in his guise as a broadcast pundit.
The International Cricket Council and England and Wales Cricket Board have also made it clear they are confident nothing untoward took place either, in last week's match against Sri Lanka when the ball was changed - catching Willis' attention - because it had gone out of shape.
"If they are doing something with the ball then it is definitely a concern, yes," De Villiers said. "But we've got no proof of that. They seem to get it to 'reverse' a bit quicker than the rest of the teams. So maybe they've just got really good skill in the bowlers."
Careful, and legal, ball-management allied to world-class skill is the recipe England insist works for them.
De Villiers added: "We've tried it as well - I think all teams try to. We haven't really managed to succeed in that. We'll try again tomorrow, and see if our bowlers can get that skill to 'reverse' the ball.
"It's something that the umpires and ICC will probably look into - why England, and some of the other teams, might get it to 'reverse' quicker or later. It is not really up to me to decide on that ... but if there is something funny happening, then it is definitely a concern."
South Africa are hoping to have their pace spearhead Dale Steyn fit, for only his second match in the tournament, as he continues his recovery from a side strain.
Steyn was able to bowl six overs in the rain-reduced tie against West Indies at Cardiff, where South Africa booked their place in the last four, but had an easy time of it at nets on Tuesday.
De Villiers said: "It will be nice to have him in the team again tomorrow. It looks like we've got a good chance. He's taken another day off, to make sure we rest him really well. I hope we can have him on the park ... but we definitely can beat England without him."
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- International Cricket Council