Queen Latifah is facing tough competition for the role of Botswanan detective PRECIOUS RAMOTSWE in director Anthony Minghella's new film - from the country's health minister, Professor SHEILA TLOU. The rapper-turned-actress - real name Dana Owens - is currently in negotiations with Minghella's production company, Mirage for the leading role in the film based on writer ALEXANDER MCCALL SMITH's novel, THE NO. 1 LADIES' DETECTIVE AGENCY. But Latifah is up against Professor Tlou, who has already portrayed Ramotswe in two stage productions in the African country. A Mirage spokesman says, "(Latifah) has previously spoken of her enthusiasm for the book, saying, 'I adore the whole series and all the characters.'" Casting agents have held auditions for the part in Los Angeles, London and Johannesburg, while casting calls in Gaborone, Botswana, were swamped by locals.