Stars at "Sinatra 100"

Lady Gaga performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS at 9 p.m. ET.

The event celebrates what would have been the musical icon's centennial birthday on Dec. 12, 2015.

John Legend

John Legend performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Harry Connick Jr. performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Tony Bennett performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Celine Dion performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Rehearsals begin for the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Nancy Sinatra and Harry Connick Jr. perform at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Katharine McPhee performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

John Legend rehearses for the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Adam Levine performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Usher performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Tony Bennett rehearses for the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Zac Brown performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Celine Dion performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Juanes performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Jeremy Renner announces at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Lady Gaga performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Seth McFarland performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.

Lady Gaga performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS at 9 p.m. ET.

Alicia Keys performs at the "Sinatra 100 - An All-Star Grammy Concert in Las Vegas," to be broadcast on Dec. 6, 2015 on CBS.