Ariana Grande and Justin Bieber duet at Honeymoon Tour Miami (VIDEO)

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."

Beliebers and Team Grande are freaking out right now.

More videos and photos from social media:

https://twitter.com/JustinSociety/status/582007353651826688
https://twitter.com/Acousticfall/status/582009473973293057
https://twitter.com/ktskankovich/status/582011166668529665
https://twitter.com/AriAlwaysUpdate/status/582004432629559296
https://twitter.com/thoughtosfyou/status/582017834705784832

https://vine.co/v/OL7ZjIPBWZH/embed/simple