Harry Maceachen's infectious laughter and excited energy captured hearts - and distracted presenters.
Born with a rare liver disease, Harry needed a transplant for his first birthday and now needs another.
His father Simon will become a living donor as no suitable match has been found from the organ donor register.
More on Harry's story and updates from Shropshire
Harry, from Shrewsbury, was born with biliary atresia which meant he had blocked bile ducts.
He was treated at Birmingham Children's Hospital and the Queen Elizabeth Hospital in Birmingham.
"The first transplant was a success, there was no problem with rejection or anything like that," said his mother Clare Maceachen.
"He's had a very rare mechanical failure - more of a plumbing issue - but hopefully after the next transplant he won't need another.
"We could still get a call right up to next week saying they've found a match, but it's looking increasingly likely it will be Simon."
"Children don't need a full liver and Simon's will grow back," said Mrs Maceachen.
"We've explained to Harry what is going to happen and I think it's been easier for him to understand he is going to be having part of daddy's tummy rather than the alternative."
Simon is a volunteer at Shrewsbury Parkrun and he and his family fundraise for the Children Liver Disease Foundation.
A four-year-old boy who stole the show during an organ donation discussion on BBC Breakfast will receive part of his father's liver.