Hollywood - The Take That! singer has been reported shooting up the male whormone testosterone.
A UK red top interview today describes Robbie as 'the dog's bollox' - er...completely rejuvenated! - following twice weekly jabs to stiffen his resolve.
Williams, 69, apparently first consulted LA medics for a human growth hormone shot after noticing 60 year-old California males whooping it up on somatotropin.
"Those Hollywood sexagenarians are suddenly looking like 40-something studs," Williams told Daily Mug Punter reporters.
But tests revealed that depletion of naturally-occuring HGH - secreted by humans in the anterior pituitary gland - wasn't the singer's actual problem.
"That's when they discovered my testosterone was missing," Williams confided.
Likely side effects may include a massive spurt in sales of his latest album and lots more lead in his autograph-signing little pencil.