"America's Got Talent" is introducing a major format update in season 21 with a new Judges' Callback round. Simon Cowell said the change was important enough that he immediately knew which guests he wanted to bring in for the occasion.

For the Aug. 4 episode on NBC, Cowell is welcoming Normani and Poo Bear as his guests. Their involvement marks a fresh twist for the long-running competition series, which the show says is doing something it has never done before.

The new Judges' Callback round stands out because "AGT" has built its identity around a familiar audition-to-live-show path. Adding a new stage suggests the series is looking to refresh the competition as the season continues airing Tuesdays on NBC.

Cowell's explanation points to the value of bringing in artists who fit the moment, with Normani and Poo Bear adding a music-focused perspective to the new round. For viewers, the headline is clear: "America's Got Talent" is making one of its biggest structural changes in years.