In preparation for Sunday's Academy Awards broadcast, Pharrell Williams ran through his No. 1 hit "Happy" some half dozen times alongside Idina Menzel, U2 and Karen O, who were also rehearsing Saturday.
The musicians are performing their Oscar-nominated songs during the awards ceremony at the Samuel Goldwyn Theater in Beverly Hills, Calif., Fox News reported. 
"All I care about is the fun," Williams said to actress Kate Hudson , who was also on hand to rehearse her part in the night's festivities.
Williams' "Happy" is nominated for the animated "Despicable Me 2;" O's "The Moon Song" is nominated for "Her;" Menzel's "Let It Go" is nominated for "Frozen;" and U2's "Ordinary Love" is nominated for "Mandela: Long Walk to Freedom."
The Academy Awards air  7 p.m. EST Sunday on ABC, Oscar.com, ABC.com, WatchABC.com and the ABC Watch App.
If you feel like doing a little preparation yourself, watch the official video for Williams' "Happy" here .
By DANIELLE HAYNES