An ecstatic Heinz on Tuesday said: "I hoped it would do well, but never expected it to do so well in only a few days."

The single Once in a Lifetime, which includes the title track and Heinz's version of Westlife's Soledad, was released on Monday.

Record company BMG expects sales to top 40 000 by the end of the week.

CD singles are awarded double platinum status after 50 000 sales. It has already reached platinum status.

The CD is selling particularly well in Heinz's hometown Stellenbosch, where Louwrens Kilian of Musica said: "We have only 25 copies left of the 150 CDs delivered here on Monday."

Four in every six clients buy Heinz's CD, he said.

"Lots of people - from young girls to their mothers - called on Monday to find out when the CD would be released."

Heinz paid a surprise visit to the shop on Monday afternoon to sign CD covers.

"Sales rocketed incredibly fast. It's great that people in my hometown support me," the Idol said from Johannesburg on Wednesday.

Mike Graham of BMG said the CD is expected to sell at least 100 000 copies countrywide. Sales may even reach 150 000 copies.

"British Pop Idol, Will Young, sold 50 000 copies of his CD Evergreen/Anything is possible during its first week in South Africa. This could be due to the fact that South Africans knew two weeks in advance that Young would be the winner," Graham said.

The series was broadcast in South Africa two weeks after it had finished in Britain.