Billy Joel helped to ring in Tony Bennett's 90th birthday with a rousing sing-a-long of "New York State of Mind" at Madison Square Garden.

Bennett sent the crowd into a frenzy when he joined Joel on stage.

After the two performed the iconic track, they embraced in a hug.

"When Billy announced it was his 90th birthday there was an audible gasp it was kind of like seeing a legend frozen in time," said a concertgoer, noting that Bennett sounded "great, as always."


Another audience member marveled, "It was definitely the loudest rendition of 'Happy Birthday' I have ever heard."


There were a number of famous faces to be seen in attendance as well, including actor Kevin James and director Judd Apatow.


Joel also surprised Bennett backstage with a cake featuring Bennett's face.