Her first acting role of 2006 was in the comedy film The Pink Panther starring opposite Steve Martin, grossing $158.8 million at the box office worldwide. Her second film Dreamgirls, the film version of the 1981 Broadway musical loosely based on The Supremes, received acclaim from critics and grossed $154 million internationally. In it, she starred opposite Jennifer Hudson, Jamie Foxx, and Eddie Murphy playing a pop singer based on Diana Ross. To promote the film, Beyoncé released "Listen" as the lead single from the soundtrack album. In April 2007, Beyoncé embarked on The Beyoncé Experience, her first worldwide concert tour, visiting 97 venues and grossed over $24 million.[note 1] Beyoncé conducted pre-concert food donation drives during six major stops in conjunction with her pastor at St. John's and America's Second Harvest. At the same time, B'Day was re-released with five additional songs, including her duet with Shakira "Beautiful Liar".

Answer this question, if possible (if impossible, reply "unanswerable"): What pop singer did a duet with Beyoncé on Beautiful Liar?
Shakira