The Wiggles' Greg Page is recovering in hospital after suffering a cardiac arrest at the band's bushfire relief concert in Sydney.
The original members of the children's group reunited to perform a sold-out concert at the Castle Hill RSL on Friday night to help raise money for the Australian Red Cross and WIRES.
But at the end of the show, Page collapsed as he walked offstage.
"Thanks for coming to support all those wonderful people doing all that great work for everyone," he said, out of breath.
He then fell to his knees just before disappearing behind a side stage curtain.
"Guys, I think we're going to end it there," Red Wiggle Murray Cook then informed the cheering crowd.
"Greg's not feeling real well. I think he's going to be OK but he's not feeling real well so I don't think we can go on with another song."
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On Twitter, the band confirmed Page had suffered a cardiac arrest and was rushed to hospital.
"Medics were called immediately and he was taken to hospital," one tweet said.
"He has had a procedure and is now recovering in hospital. We appreciate your kind messages and concern," said another.
A NSW Ambulance spokesperson said paramedics were called to the RSL around 10pm following reports a 48-year-old man had gone into cardiac arrest, according to reports.
The other band members then returned to the stage without Page to sing Hot Potato.
"We're going to sing it for Greg and hope he gets better real quick," Blue Wiggle Anthony Field said.''
Page has suffered from fainting spells and chronic fatigue in the past, and hung up his yellow skivvy in 2006 after being diagnosed with a condition called orthostatic intolerance.
The condition left him unable to perform and walking with the aid of cane, though he went on to briefly return to the group a few years later.
Friday's concert, which was being live-streamed online, was the first time the band's founding members had played together since 2012.
Fans said Page had been "a champion" for powering through the show for those in need.
The group is scheduled to perform another show on Saturday night.