Justin Bieber joined Ariana Grande during her concert at The Forum in Los Angeles, California last Wednesday and during their performance of "As Long As You Love Me," Justin Bieber reportedly asked the "Love Me Harder" singer to stand in front of him while he touched her inappropriately according to TMZ.

Ariana was dressed in sparkly hotpants and a crop top, and her trademark cat's ears. Meanwhile, Justin Bieber kept things casual in a shirt, leather pants and sneakers.

Ariana's boyfriend Big Sean, who was in Canada during the concert, reportedly got wind of the incident and threatened Justin through Twitter.

"This kid is about to learn not to touch my girl like that. Beliebe that," Big Sean is thought to have tweeted. The tweet was later taken down from the account. Big Sean also reportedly posted a photo of Bieber with his hands all over Ariana, with the caption "Wow."

Soon after the report, TMZ learned from their sources that the Tweet was a fake.

Justin Bieber himself tweeted about the performance, though he only said thank you to Ariana for having him as a guest performer. "Love the stage. Thanks for having me @ArianaGrande and thanks LA. Gotta tour again soon :)"

His tweet earlier that evening never mentioned his planned duet with the singer. Justin even teased his millions of Twitter followers with the following post: "What should I do tonight? Hmmmm."

This was not the first time that Justin Bieber made a surprise guest appearance during Ariana Grande's concert. Earlier this month, The Biebs also surprised Ariana's fans when he took to the stage during the latter's concert in Miami. Justin Bieber and Ariana Grande share a manager, Scooter Brown.

Currently, Justin is reportedly working on his fifth album, which is going to come out soon. In an interview with Ryan Seacrest, Justin revealed that the inspiration for his new album is his ex-girlfriend Selena Gomez. "A lot of inspiration comes from Selena," he said on the interview.