Rihanna vs. Ariana Grande beef? Drake's girlfriend hysterical during iHeartRadio performance, laughing at Chris Brown collaborator? [WATCH]

Rihanna won top-honor at the first-ever iHeartRadio Awards held in LA on Thursday (May 1) - "Artist of the Year." Check out Riri's acceptance speech below:

The "Pour It Up" songstress was ecstatic, and definitely turned heads in her funky, goth-inspired getup.

(Getty Images)

But there's another video from the event that's currently going viral online...

RiRi cracking-up during Ariana Grande's standout performance: 

What perfect timing when the cameras turn to get the reaction of Drake's girlfriend - she can't stop laughing!

Maybe someone at her table made a joke at a rather inopportune time? Or was Rihanna really hysterical over the "Problem" songstress' performance!?

Now rumors suggest there's a new "feud" brewing in Hollywood.

Grande IS coming-out with a new collaboration featuring RiRi's ex, Chris Brown. Maybe that's why the Barbadian beauty broke-out in a fit of giggles?

What do Mstars fans think?

RELATED: Ariana Grande dating Jai Brooks (again)? 'Problem' songstress spotted kissing & hugging ex-boyfriend at iHeartRadio Awards [PHOTOS]