The former Dr. Feelgood star, who was diagnosed with inoperable cancer in January, 2013, had major surgery last month (Apr14) to cut out a huge tumour on his pancreas.
His pal and collaborator Daltrey has now revealed Johnson is on the mend after undergoing the experimental operation, during which he had the tumour, his spleen, pancreas and parts of his intestines removed.
The Who frontman has even suggested Johnson could make a full recovery despite only being given months to live by doctors during his original diagnosis.
The Pinball Wizard singer tells the Bbc, "He's in hospital. He's been in and out for two weeks, he's doing really well... He's lost an awful lot of his body, but he's still here. Which is one up from being dead.
"He's getting out of bed and grunting, which is exhilarating for him I'm sure, and we look forward to him making a full recovery... There is a chance (of a full recovery), but it's an operation that's never been tried before. He's an experiment. His whole life has been an experiment."
Daltrey also insists he is already planning to return to the studio with Johnson for a follow-up to their album Going Back Home, released in March (14).
He adds, "It's going to take a long, long time. But if he does (come back) we're going to make part two of the record that we rushed out."