Ariana Grande and Justin Bieber performing "As Long As You Love Me" in Miami

Justin Bieber was Ariana Grande‘s surprise guest at her “Honeymoon Tour” stop in Miami on Saturday. They sang “As Long As You Love Me” and “All That Matters.”The singer crashed Ariana Grande’s Honeymoon Tour on Saturday night in Miami, and they duetted on Bieb’s “As Long As You Love Me.”