Usher, Katy Perry and the cast of 'Glee' were among the pop stars booked to mark the start of President Obama's second term.
The official inauguration will take place on Monday, but the celebrations started last night with a Kids' Inaugural Concert for children and military families in Washington DC.
Beyoncé, Kelly Clarkson and James Taylor are expected to sing at the president's official inauguration.
Usher has postponed his UK and European gigs after landing a role as a coach on the US version of talent show The Voice.
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R'nB star Usher headlined the first night of the iTunes Festival at Camden's Roundhouse in London. The festival takes place all through September.
R&B singer Usher will have the honor of playing boxing legend Sugar Ray Leonard in an upcoming movie. The film is called "Hands of Stone" and is biopic about Panamanian boxer Roberto Duran. Usher is also working in the studio on his seventh album.
