Ora has been wearing outfits similar to that of Rihanna's for a while now, but the red gown she wore to the MTV EMAs seems to be the final straw.
The red gown Ora wore for the red carpet looked very similar to the outfit the 'Umbrella' hitmaker wore at the American Music Awards.
And the 'Hot Right Now' songstress even brought an umbrella onto the stage during her performance, reported Sun online.
Rapper Jay-Z seems to have been brought in for crisis talks to resolve the dispute as he owns label Roc Nation which manages Rihanna and Rita.
"Rihanna was furious when she spotted Rita Ora's dress for the VMAs, a rose gown that looked like one she wore in 2010.
"But she was even more annoyed when Rita went on stage using an umbrella as a prop. When Rita started her career, Rihanna thought it was cute that she was copying her look. But now she's getting angry, especially as Rita is getting a following by using her old tricks," said a source.