(entertainmentwise.com) - Madonna's upcoming world tour has been thrown into turmoil after the pop superstar injured her ankle, just two weeks before the live shows are due to kick off.The almost 50-year old is currently in New York rehearsing for her Sticky & Sweet tour which will begin in Cardiff Wales on 23 August.And she was photographed this weekend nursing a heavily bandaged foot, prompting fears that she may not be fully fit for the first date of the tour.The mammoth trek will cover Europe and North America and will wrap up in Mexico City on 30 November.