Watch: Andrea Bocelli, Celine Dion, Lady Gaga's stirring 'The Prayer'

(From left) Lady Gaga, Celine Dion and Andrea Bocelli brought "One World: Together at Home" to a close with soaring four-part harmony with 'The Prayer'. Photos: Reuters

Lady Gaga, John Legend, Celine Dion and Andrea Bocelli brought "One World: Together at Home" to a close with soaring four-part harmony – and accompaniment by piano virtuoso Lang Lang – with The Prayer, the song that became an inspirational standard after Dion and Bocelli recorded it separately and together 21 years ago.

It was the sole appearance on the two-hour prime-time telecast by Bocelli, who might actually count as the biggest pop star of the week, after his Easter Sunday live-stream from Milan was viewed by more than 30 million people on YouTube.