Rocker John Mayer is slowly building up his live setlist as he continues to recover from throat surgery because there are some keys his vocals simply cannot reach yet.

The singer/songwriter, who struggled with vocal problems for some time, had to have muscle-freezing agent Botox injected into his throat last year (12) to cure his ongoing issues, and he only recently returned to the stage.

However, the Your Body Is A Wonderland hitmaker admits he's still not completely back to normal and he has to try reaching new notes each day to determine what he can and can't sing on the road.

He tells U.S. breakfast show Today, "It's different now, just because the Botox is sort of clearing out so it's like a gift that keeps unwrapping itself... 'Oh, I can sing this song now.' So it looks as if there are certain songs I won't play, (but) it's just I can't."

And Mayer insists he always had faith in the wonders of medicine to restore his voice so he could sing again: "There was never that chance (of never singing again). Thankfully I always knew that there was gonna come a day when I would sing again, it was just a matter of when."