SINGER Christy Dignam is in rehearsals and expects to perform at Friday's fundraising concert in his honour.
Some of the biggest names in Irish music are set to take to the stage to help raise money for the Aslan man's medical bills.
U2 will perform This Is via satellite link from their studio in New York.
Dignam (52), who is undergoing treatment for cancer, was expected to be a spectator in the Olympia Theatre, but he has defied the odds.
"We're having our first rehearsal with Christy today.
"It really would have been too much for him to sit there watching all these amazing performers singing his songs, and not being able to join in," Aslan guitarist Billy McGuinness said.
Although the line-up – which includes the first solo performance from Mark Feehily since leaving Westlife, the Pogues' Shane MacGowan, Voice star Bressie and Danny O'Reilly of the Coronas – ensured tickets sold out within hours of going on sale, not all Aslan fans have welcomed the addition of Jedward.
"Jedward? Are you f***ing serious," complained one fan on Aslan's Facebook, while another said: "The likes of Jedward are undoing all the good that Christy and the whole Aslan crew have ever done for Irish music".
However Billy McGuinness asked that Aslan fans treat Jedward with respect.
"John and Edward came forward and asked to help. We're delighted to have them.
"They picked their own favourite Aslan song and we'll be backing them.
"Having Jedward on board with U2 has really helped us get worldwide interest in streaming the event, so we are grateful."
Over 100 venues worldwide are so far streaming A Night For Christy.