Andrew Lloyd Webber subs for Questlove as DJ at Michael Jackson bash

Call it “the phantom of the DJ.”

Questlove was meant to deejay a Tony nomination party for “MJ the Musical” Wednesday, but when the “Tonight Show” bandleader couldn’t make it at the eleventh hour, Andrew Lloyd Webber stepped in to spin at the Michael Jackson celebration.

Sources tell Page Six exclusively that Questlove was scheduled to play tunes for the Broadway show’s party at Tavern on the Green to celebrate its 10 nominations, but a spy says, “He had to pull out due to illness.”

As a replacement, Questlove, 51, sent along his pal — and noted Jackson musicologist — DJ Spinna to man the decks at the party, where guests included MJ’s kids Prince Jackson and Paris Jackson as well as the late King of Pop’s brothers.

“Andrew Lloyd Webber, who spins under the name DJ Webz, caught wind that Spinna would be manning the turntables and hit the DJ booth to lend his support,” a source says.

The “Phantom of the Opera” and “Cats” legend, 74, previously deejayed various Broadway shindigs for theater A-listers.

Cutting a rug at the upscale party was Tony nominee Myles Frost, who plays Michael on stage and was spotted “being treated like family” by the Jacksons in a “VIP room,” we’re told.

Frost, 22, was seen dancing with Prince 25, and Paris, 24, to Spinna’s wild mash-ups of Michael’s hits.

The Jackson family attended a performance of “MJ” earlier that night.

“They were spotted wiping away tears during the number ‘I’ll Be There,'” a spy shares.

Page Six previously reported that Paris was sent the cast flowers.

Other stars who’ve seen the musical include Alicia Keys, Michelle Williams of Destiny’s Child, Angela Bassett, Nick Cannon, Michaela Coel, Jane Krakowski and Clive Davis.

A rep for Questlove didn’t immediately get back to us.