Audiences tuning into the FireAid benefit concert for Los Angeles on Thursday night (Jan. 30) were surprised with an early treat when pop superstar Billie Eilish made a surprise appearance alongside Billie Joe Armstrong and the rest of Green Day for a stirring opening performance.

Billie Joe Armstrong and Billie Eilish. Green Day got things started at the Kia Forum, where they surprised fans with Eilish to help them perform, "Last Night on Earth" from 2009's 21st Century Breakdown.

Bille Joe Armstrong said it was an honor to "share the stage" with Billie Eilish at the FireAid benefit concert, which is expected to raise over $100 million in donations.