Robbie Williams is expected to perform with Take That tomorrow night
The `Bodies` hitmaker - who left the group in 1995 following a rift with his bandmates - has reportedly agreed to performwith Gary Barlow, Howard Donald, Jason Orange and Mark Owen for the first time in 15 years for British charity Children In Need.
Former Beatles star Sir Paul McCartney is also believed to be joining the band on stage at London`s Royal Albert Hall, though the supergroup are still discussing what to sing.
A source told Britain-s The Sun newspaper: "The reunion is go. Robbie is utterly thrilled about it. He`s been dreaming of performingwithTakeThat again for years and now it`s going to happen.
"Gary is looking forward to singing with Rob again, but landing Paul McCartney is without doubt his biggest coup. They haven`t decided what they are going to sing together, but something will take shape in rehearsals."
Other performers at the charity event include Girls Aloud star Cheryl Cole, `Bleeding Love` hitmaker Leona Lewis and -Bonkers- rapper Dizzee Rascal.
Robbie - who has previously battled alcohol and drug addictions - walked out on the band in 1995 and famously refused to speak to bandmate Gary for 10 years.
But in 2005 the pair made contact and have since been writing together.
Meanwhile, TakeThat bandmate Mark got his sister to sing at his wedding.
The pintsized star asked Tracy to performwith a choir when he tied the knot last weekend to Emma Ferguson, and she wowed the congregation with a rendition of Judy Collins` version of Amazing Grace.
A source at the service said of Tracy`s performance: "She was amazing. Singing definitely runs in the family."