Singer Jennifer Lopez was noticeably indifferent to Nicki Minaj’s performance of her single “Anaconda” at Fashion Rocks 2014 on Tuesday. Her reaction has reportedly caused speculation on whether a feud exists between the two bootylicious performers. Lopez and Minaj both performed at the event in Barclays Center in Brooklyn, and both their songs were about butts.

One theory discussed by HollywoodLife.com is that Lopez was not pleased because her ex-boyfriend Casper Smart was the choreographer for Nicki Minaj’s “Anaconda” video and her Fashion Rocks performance. However, a source told the site that Lopez’s beef with Minaj stems from issues concerning the top reality TV series American Idol.

“Nobody at American Idol likes Nicki Minaj, there is story after story on how difficult she was during her tenure and JLo has heard it all. And JLo is mad at Nicki for it and her role in bringing down the show when she was on it, especially since it was JLo’s show beforehand,” said the source.

The source added that Lopez knew that audiences were turned off by American Idol when Minaj was on the show and that the Latina singer has made it her mission to bring the fun back to it. “So the beef people caught onto is based on all things Idol and not Casper,” said the source.

Lopez also performed her new single “Booty” at Fashion Rocks, bringing with her an entourage of wiggling derrieres onstage. She wore a very short sparkly dress, which she raised during the performance to show a high-cut silver-sequined bikini that revealed her almost-nude butt.

It’s the battle of the booties for Jennifer Lopez and Nicki Minaj: http://t.co/BqPBgTCQh7 pic.twitter.com/DRRZN5z2Ms

— The Sun Showbiz (@TheSunShowbiz) September 10, 2014

Earlier that evening on the red carpet, she wore a dress that had slightly more coverage but was no less sexy than the one she wore for her performance. Her elegant dress was a slinky black number made by Atelier Versace with gold-plated detail, cut-outs and a thigh-high split.

RED CARPET RECAP: J.Lo, Nicki Minaj, Rita Ora & more work it for Fashion Rocks http://t.co/oRMxApM2s1 pic.twitter.com/Q3SAyOQOOZ

— GlobalGrind Style (@GlobalGrindStyl) September 10, 2014