Taylor Swift just elevated her feud with Katy Perry to a whole another level as she performed "Bad Blood" with the use of a shark prop.

The prop by Calvin Harris' girflriend was in reference to Katy Perry's Super Bowl XLIX performance where she danced with shark mascots.

"On Sunday, the 25-year-old country-pop crossover performed her hit Bad Blood in Foxborough, Massachusetts during the latest stop in her 1989 tour and possibly took a jab at her 30-year-old frenemy," said Daily Mail.

"In the numerous fan-posted videos, Taylor can be seen letting out a little laugh when she notices a shark puppet peeking over her left shoulder," the article added.

"Bad Blood" was reportedly a reference to the feud between Taylor Swift and Katy Perry when the latter "stole" the backup dancers of Calvin Harris' girlfriend before she went on tour. The shark dancer on the left of the "Fireworks" singer on her Super Bowl performance was supposedly one of those dancers.

In an interview with Rolling Stone, Taylor Swift talked about female artists whom she believed to be a fake.

Calvin Harris' girlfriend explained, "For years, I was never sure if we were friends or not. She would come up to me at awards shows and say something and walk away, and I would think, 'Are we friends, or did she just give me the harshest insult of my life?'"

"[Then last year], she did something so horrible I was like, 'Oh, we're just straight-up enemies.' And it wasn't even about a guy! It had to do with business."

"She basically tried to sabotage an entire arena tour. She tried to hire a bunch of people out from under me. And I'm surprisingly non-confrontational - you would not believe how much I hate conflict. So now I have to avoid her. It's awkward, and I don't like it," she added.

But a source told Hollywood Life that the fued between Taylor Swift and Katy Perry runs deep.

"Katy and Taylor are the definition of oil and water," the insider said. "They both have completely opposite personalities and Taylor just rubs Katy the wrong way. Katy feels that everything Taylor does is completely fake and annoying and she really doesn't care for her."