Rising pop star Lady Gaga was “hysterical” with grief upon learning legendary hitmaker Michael Jackson had died, according to reports out of the UK.

As we all know by now, the King of Pop died on Thursday at the age of 50.

The “Love Game” singer reportedly cancelled all interviews before her debut at Britain’s Glastonbury Music Festival after hearing the news and refused to leave her tour bus.

“Gaga was hysterical with grief. She could not be consoled and spent the day on the phone to her producer RedOne in America,” says a source in the star’s camp.

“They penned hits ‘Poker Face’ and ‘Just Dance’ together. He had been working with Michael on new material recently and was beside himself.”