Fans went crazy when Pop superstar Justin Bieber, 21, once again showed up on stage during Ariana Grande's, 21, concert in Inglewood, Calif. on Wednesday and the two performed three songs together -- "Love Me Harder," "Where Are U Now," and "As Long as You Love Me."

Two weeks ago in Miami, Bieber showed up on stage during Grande's show for the first time.  In a Tweet before the L.A. concert, Bieber already hinted to his fans that he was up to something special Wednesday night and later thanked Grande for letting him join her on stage.

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During their duet, Grande was seen giggling as Bieber put his arms over her shoulder, which reportedly irked her boyfriend rapper, Big Sean, 27.  It was rumored that Big Sean became unhappy with the embrace between the pop pair and reportedly took to Twitter to vent his disapproval.   

In one supposed deleted tweet going around on social media, he warned: ''This kid is about to learn not to touch my girl like that. Beliebe it. (sic)''

Grande and Big Sean are said to be in a ''serious'' relationship after having dated for over a year.  However, Bieber and Grande's sweet duet didn't deter the fans from remarking on social media that the concert duo looked ''cute together'' and should ''get together''.

Meanwhile, a rep for Big Sean tells TMZ that Sean's supposed Twitter threat was actually a fake and that Bieber and Sean are good friends and that "he and Ariana are just fine."

TagsJustin Bieber, Ariana Grande, Big Sean, Concert, Twitter rant