Lamar, 37, and SZA, 35, have enjoyed a big brother/little sister bond ever since they became label mates on TDE Records and ascended to the top of their respective genres. Joint shows can be messy, especially when they pull a particular artist out of their comfort zone.

The rapper and R&B star are taking victory laps for smash hits and albums. But their co-headlining tour is still threaded with angst and reflection.

Kendrick Lamar performed Drake diss tracks "Euphoria" and "Not Like Us" on the Grand National Tour with SZA, keeping his beef with Drake alive.