Billy Joel fans were surprised when Olivia Rodrigo made an appearance at his Madison Square Garden show on Thursday (August 24)

Rodrigo performed her hit, “Deja Vu,” and Joel’s “Uptown Girl.”

If you know how her hit “Deja Vu” goes you know that Rodrigo says, “I bet she knows Billy Joel ’cause you played her ‘Uptown Girl.'”

Obviously the crowd went wild because as she sang her famous line, she pointed at Joel.

She then went on to perform the legendary song with Billy Joel himself.

Olivia made the appearance following a reported breakup with a music executive. 

What legendary artist would you pair with a newer artist?