It drew one of the biggest roars of the night at the Tony Awards: Alicia Keys was performing a medley from her Broadway musical “Hell’s Kitchen” on Sunday when she walked out of the auditorium and was shown joining Jay-Z on a marble staircase for “Empire State of Mind,” their 2009 love song to New York City.

“Had to do something crazy — it’s my hometown!” Keys said as the cameras followed her walking out of the auditorium at the David H. Koch Theater in Lincoln Center. A video screen onstage cut to Jay-Z, the Brooklyn-born rapper and mogul, as he performed from the curved marble staircase just outside the auditorium. Keys was seen joining him.

There was a reason Jay-Z never appeared on the Tonys stage except in video form, though. In a savvy trick of the production, the reunion between two of music’s biggest stars was pretaped and carefully edited to seamlessly make it appear part of the live performance on Sunday night’s Tonys telecast, according to two people with knowledge of the telecast preparations who were not authorized to speak publicly about them. (New York Magazine reported earlier that the segment had been pretaped.)

Live or taped, the duet became one of the biggest moments of the night. The Broadway crowd went wild as Jay-Z closed with, “New York City in the Tonys tonight!”