Niall Horan was left with a tough decision to make.
Director Rob Marshall laid out the reasons in a new interview.
The two have been teasing a collaboration for days.
The new teaser -- soundtracked by a Beach Boys hit -- also provides the first true look at Barbie Land.
Team Niall's singers were hard to separate.
The duet that had all the makings of a LaLa Land special -- drama, struggle, tears and success.
The full episode airs on Tuesday (April 4) on NBC.
Get ready for 'One Last Ride: Blake Shelton's Final Season,' folks.
The soundtrack arrives a month before Guardians of the Galaxy Vol. 3 hits theaters on May 5.
An on onlooker also captured video of the pop star appearing to perform a musical number for the sequel.
