Justin Bieber can't keep his hands off Ariana Grande

Justin Bieber hugs Ariana Grande during her performance. Photo / Twitter

He surprised Ariana Grande fans by hitting the stage for a sultry duet with the star during her Miami tour stop last month.

And it looks like Justin Bieber can't get enough of the spotlight, or his pal Ariana, as he joined the singer for another surprise appearance during her concert at The Forum in Inglewood, California on Wednesday.

The 21-year-old beauty brought out her long-time friend for a rendition of her hit Love Me Harder, with Bieber taking on the verses originally sung by The Weeknd.

Soon after the show of affection, Big Sean was thought to have tweeted, "This kid is about to learn not to touch my girl like that. Beliebe that."

But TMZ heard from sources that the tweet was a fake and that the rapper was never mad at the Baby singer.

Ariana was dressed in one of her trademark skimpy costumes for her California gig, showing off her killer legs in a pair of sparkly hotpants paired with a matching crop top.

As she finished off her look with a pair of her favourite spangly animal ears and some super high heels, 21-year-old Justin couldn't keep his eyes or hands off the star.

As Grande belted out her verses of Love Me Harder, the hit-maker wrapped his arms around the pretty pop star, nuzzling into her neck.

Bieber kept things casual in a black t-shirt, leather trousers and sneakers for his surprise appearance, adding a backwards baseball cap to his stage look.

Not to be outdone by Ariana's sexy look, the teen idol lifted up his shirt at one point as fans went wild over his abs.

As well as Love Me Harder, Grande let her pal take to the stage solo to perform his song Where Are You Now, with the help of some back up dancers.

Grande then returned for a duet performance of Bieber's hit As Long As You Love Me.

Fortunately this time around Bieber's performance went off without a hitch. Two weeks ago in Miami he managed to forget the lyrics to Love Me Harder, forcing Ariana to step in.

Bieber gushed that he'd had the time of his life singing with his friend, telling his Twitter army afterwards that it's inspired him to get back to his own live performances:

"Love the stage. Thanks for having me @ArianaGrande and thanks LA. Gotta tour again soon :)" he wrote.

Love the stage. Thanks for having me @ArianaGrande and thanks LA. Gotta tour again soon :)

— Justin Bieber (@justinbieber) April 9, 2015

Earlier in the night, Bieber teased his supposed lack of plans for the evening, keeping his secret appearance well under wraps.

"What should I do tonight? Hmmmm," he asked his 62 million followers.

Bieber and Grande's second team-up in as many weeks is thanks to their shared manager Scooter Braun, who has been working hard with Justin as he records his fifth studio album.

Last week Bieber revealed he has been pouring his emotions into the songs for his anticipated new record, which is being produced by Kanye West.

"A lot of inspiration comes from Selena," he told Ryan Seacrest on his On Air radio show of the influence of his ex girlfriend Selena Gomez.

Bieber and Gomez's public romance first began in December 2010, when the pair were still in the early stages of their fame.

"It was a long relationship that created heartbreak and created happiness and a lot of different emotions that I wanted to write about," Bieber explained when asked about his ex.

"I'm pretty silent about what I've been going through and just growing up in this life is hard. So I want to translate that," added Bieber.

His latest music project comes after he released 15 tracks on his Journals EP which was only available for purchase on iTunes for two weeks in late December 2013.

- Daily Mail