Madonna has postponed the first of four shows in Argentina.

Representatives of River Plate Stadium say they have postponed the pop star's opening concert at the request of the production company. She will still perform as scheduled in Buenos Aires on Thursday, Saturday and Sunday.

Local news media are reporting that some of Madonna's sound equipment hasn't arrived due to flight delays, so the concert could be rescheduled for Monday.

Local production company Time 4 Fun wouldn't comment when contacted by The Associated Press on Wednesday.

Madonna kicked off the Latin American leg of her "Sticky & Sweet" world tour last week in Mexico City.

From Buenos Aires she heads to Chile and Brazil.