"Rihanna confessed to Oprah Winfrey that she still loves Chris Brown," Rivers tweeted. "Idiot! Now it's MY turn to slap her."
Never one to back down from a good Twitter tussle, Ri responded with a dig against the 79-year-old comedy legend's age.
"@Joan_Rivers wow u really do get slow when you're old huh?" Rihanna tweeted, later deleting the message.
"Slap on some diapers," she added in a follow-up post, which she's opted not to take down.
Taking the high road and ending -- one hopes -- the skirmish on a concerned note, Rivers explained that she's looking out for the singer's well-being. She might also be looking out for her ratings, as she invited Ri to appear on her E! show.
"Honey, @Rihanna, everyone knows: If he hit you once, he'll hit you again," she tweeted. "Read the statistics. PS – Love to have you on Fashion Police!
Watch an Excerpt From Rihanna's Interview With Oprah
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