Katy Perry may have finally made peace with longtime pop-nemesis Taylor Swift, but it seems the "Swish Swish" singer might be engaged in yet another glitzy cold war.

According to The Sun, former BFFs Rihanna and Perry are completely on the outs, and actually have been for more than a year. The site says that Rih most recently left Perry off of her guest list for a post-Met Gala party at New York City's Up & Down, and Katy was less than pleased. Still, Katy was a good sport about snapping a photo with Rih, The Sun reported.

"Because Rihanna was chairing the Met Gala, she had to pose with a lot of the celebrity guests but it was really uncomfortable when she was asked to have the photo with Katy," the source said. "They used to be close but Rihanna’s expression in the photo says it all...Katy was upset about the whole situation because Rihanna was cold to her and she wasn’t invited to her after-party.”

The Mirror had previously reported in September 2017 that Katy and Rihanna's friendship had "fizzled out," and they'd even gone to "great lengths" to avoid each other at big-time events.

Rihanna also noted when asked if she'd join Katy on the American Idol judging panel: "I don’t know, it depends on how bored I am.”

"They didn’t have a big bust-up over one specific thing, but over time their friendship has gone from being one of the strongest to practically nonexistent. Katy was pretty gutted about it," a source told the site. "Some pals have said they just grew apart when she started dating Orlando Bloom...but the reality is, nobody knows exactly what went down between the pair.”

Katy Perry + Rihanna: Friends Turned Enemies?