Sir Mick Jagger has been ''singing his ass off'' in preparation for The Rolling Stones' 50 and Counting shows.
The legendary 'Satisfaction' rockers started their run of shows at London's The O2 venue on Sunday (25.11.12), and the singer has been giving it all in rehearsals according to touring keyboard player Chuck Leavell.
He told Rolling Stone magazine: ''As you probably know, they've had that thing over the past year where they get together a couple times a week, so [Keith Richards, guitarist] has built his chops back up, and you know Mick is singing his ass off.
''It's been about five years, so when you do finally get together and get in the same room and get behind the instruments and crank it up, man, it just reminds you how much we all love this stuff.''
Chuck - who's been playing with the group live since 1982 - also has a special role when it comes to rehearsals, putting the set list together with the group - which also features guitarist Ronnie Wood and drummer Charlie Watts - to encompass all the different aspects of their long career.
He added: ''I can't remember the last time Charlie Watts or Ronnie Wood have come up and offered [set list] suggestions. ''Mick and I talked about it on several occasions, really, in the early stages of the rehearsals, and I made up varied lists. I make up a list every day of what I think the band should be rehearsing.
''We have tried to look very hard at all of the various eras of the band's career and tried as best as possible to represent those eras. Fifty years is a long time, man.''
The Rolling Stones will play another show at The O2 on Thursday (29.11.12), before moving over to the US for shows at the Barclay Center, New York City, on Saturday December 8 and the Prudential Center, New Jersey on December 13 and 15.