Robin Gibb has a "50/50" chance of "coming through" his health problems, says a friend.
The Bee Gees star has colon cancer and it is thought to have spread to his liver.
He recently fell into a coma after developing pneumonia, but has now regained consciousness.
His friend Jim Dooley is very close to Robin and has opened up about his condition.
"He can't speak at the moment because he has a tracheotomy, and he has to communicate by blinking his eyes," he told British newspaper The Telegraph.
"Dwina [Robin's wife] has said that because he spent so long in a coma there are a lot of things he will have to learn to do again if he comes through it. He will have to re-learn how to walk.
"It's 50/50 whether he comes through this but Dwina is a wonderful woman and she is giving him all the love and TLC you can give."
Jim has been working alongside Robin to help raise money for the Bomber Command Memorial, which is in honour of UK air force members who died in World War II.
He explained messages of support for the 62-year-old musician are still pouring in.
"He is receiving prayers and blessings from every religion all over the world and I'm told there is a special blessing on the way from the Pope," Jim explained.
"The plan is to get his strength up so he can resume chemotherapy treatment for his cancer."