Bieber's mind went blank when he joined Ariana onstage in Miami.
Justin surprised thousands of screaming tweens last night when he took the stage during "Love Me Harder" at the Miami show of Grande's "Honeymoon Tour."
He struggled to remember the lyrics of The Weeknd's verse and the stage fright stayed with him as the pair went on to perform Justin's own hits "All That Matters" and "As Long As You Love Me."
Luckily, one of his beliebers Ariana was on hand to help him get through his first arena performance in over a year as she sang the hell out of his songs and even performed her boyfriend Big Sean's verse of "As Long As You Love Me."
The crowd didn't seem to care about the mishaps very much as they were too infatuated by the two 21-year-olds being onstage together.
And left-side-only-please diva Ariana wasn't exactly seething either as she tweeted her thanks to the Biebs later on, while he took to Instagram poking fun at the lyrical mishaps, saying "Had fun with u Ariana, even tho I forgot all the words haha."
Check out the performances below.
Better luck next time, JB!