Stadbally, Ireland - Billie Eilish brought the house down at Electric Picnic despite her recent bout with a tough illness.

The show must go on!

The 21-year-old singer gave her fans a message ahead of her performance in Ireland, revealing that her health was struggling at the moment.

"i am really, really sick. and honestly really suffering," she wrote on Friday. "you know me and you know that i wouldn't cancel a show even if i was like literally dying... (this does feel pretty close tho lol).

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She concluded her message by asking fans to give her some support to push through the performance, and they certainly delivered!

Footage from the Irish music festival showed Eilish performing several of her biggest hits, including Happier Than Ever, bury a friend, What Was I Made For?, and my strange addiction.

For the festival, the Grammy winner rocked a white Nike basketball jersey with black-and-red basketball shorts. Eilish showed off her newly dyed matching black-and-red hair after she ditched her baseball cap.

Also performing at the star-studded event was former One Direction star Niall Horan, who was spotted in the crowd watching Eilish's headlining set on Friday.