By Paige Gawley
Will Heath/NBC/NBCU Photo Bank via Getty Images
Justin Bieber is ready to take the stage! A source tells ET that the 26-year-old singer has been rehearsing "tirelessly" for "three-plus weeks" in Los Angeles ahead of his New Year's Eve performance, his first live concert in years.
"Performing on stage is his absolute favorite thing to do, and he is super excited to get back on stage for a real show -- his first [concert] in almost four years!" the source says.
As for what he'll play for his comeback concert performance, ET's source said the setlist will be wide-ranging.