(AllHipHop News) Jay-Z has inked a deal worth millions of dollars, to perform at a swanky bash to celebrate the opening of the Cosmopolitan of Las Vegas on New Years Eve. The New York Post reports that lavish party is being planned by party planner Colin Cowie, who has also booked Coldplay's Chris Martin to perform at the invite-only event. Jay-Z will deliver his own set, as will Chris Martin. The pair will then take to the stage together to thrill the guests with mashup performance of their best known hits. According to the Post, Jay-Z's wife Beyonce is also in the process of securing a performance in Las Vegas on New Years Eve, so the married couple can celebrate the holiday together. In related news, Jay-Z and Beyonce recently landed in the Guinness Book of World Records for being the "Highest Earning Power Couple," by raking in over $122 million through June of 2009.