Lance Bass joins Backstreet Boys onstage during Vegas concert

March 21 (UPI) -- Lance Bass of 'N Sync fame joined forces with fellow '90s boy band the Backstreet Boys onstage recently during a concert in Las Vegas.

"We really showed @lancebass the shape of our hearts tonight. Thanks for coming by #BSBVegas, brother!" noted the official Instagram account for the Backstreet Boys alongside a clip featuring the group singing "Shape of My Heart" alongside Bass as fans cheered.

"Only at #BSBVegas.. @lancebass" they wrote in a second post as Bass is seen singing into a microphone as Backstreet Boys members Kevin Richardson and Nick Carter huddled around him.

The concert is part of the Backstreet Boys Las Vegas residency at Planet Hollywood which began in March. The stint is scheduled to last until July 1 for a total of 26 shows.

Bass last made headlines in February when he revealed that 'N Sync would reunite for the unveiling of their star on the Hollywood Walk of Fame and that the group would be releasing a vinyl edition of their 1998 Christmas album, Home for Christmas.