Bad blood was percolating in the Philadelphia stratosphere at Taylor Swift's Eras Tour on Saturday night.

Performing her second of three shows at Lincoln Financial Field in Philadelphia, Swift's lively concert was interrupted by a disturbance off-stage.

While performing her hit song "Bad Blood," Swift could be heard yelling at an unknown individual, "She's fine. She wasn't doing anything!"

As the song builds to the chorus, Swift grows more agitated, yelling, "Hey! Stop!"

TAYLOR SWIFT SPEAKS OUT AFTER INJURING HERSELF DURING ERAS TOUR: 'IT WAS MY FAULT COMPLETELY'

Taylor Swift in her Reputation era jumpsuit sings into a microphone while on stage at the Eras Tour

Taylor Swift was heard yelling "stop" while on stage, in the middle of performing her song "Bad Blood." (Bob Levey/TAS23/Getty Images for TAS Rights Management)

Fox News Digital spoke to a fan at the concert, who detailed their confusion of the situation.

"As Swifties we were confused whether it was part of the song or not because of the nature of the song," she explained of the hit track off Swift's 1989 album.

"But we knew something was off, especially because Taylor doesn't speak to her fans that way."

Taylor Swift in an all-jean outfit sits on stage with sparkly boots and holds a microphone during the Eras Tour

Although the song "Bad Blood" is feisty, fans were unsure if Taylor's ad libbing was part of the show or not. (Lisa Lake/TAS23/Getty Images for TAS)

A representative for Swift did not immediately return Fox News Digital's request for comment.

The 12-time Grammy Award winner uttered one final "Stop" before strutting across the stage and continuing on with her set. She never addressed the incident, although video of the contentious moment went viral on social media.

Fans immediately defended Swift, explaining she was yelling at a security guard in an effort to protect her fans.

Taylor Swift in a pink dress plays behind a brown piano with a guitar leaning up against it at the Eras Tour

The video of Taylor Swift yelling mid-concert went viral on social media. (Lisa Lake/TAS23/Getty Images for TAS)

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People on social media were eager for the fan to come forward and explain exactly what happened.

In a video shared to her friend's TikTok account, Maryland resident Kelly Kelly revealed she was the fan Swift was protecting.

"Basically, the guard had been harassing our group all night… He just kept telling us not to touch the rail, and like every time we did anything, he was like on top of us," she began.

"We're dancing, we're having fun, and he didn't like it," she continued. "Taylor noticed that I was having fun and that he didn't like it, and she didn't like it. And then he basically like got escorted out, and then they offered us free tickets for tonight."

Taylor Swift holds the microphone during the Eras Tour playing on a pink guitar

The fan that was protected by Taylor Swift at her Eras Tour identified herself on Twitter. (Lisa Lake/TAS23/Getty Images for TAS)

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The video quickly amassed more than 1 million likes, prompting Kelly to create her own account and thank Swift for standing up for her.

Kelly also spoke to GMA about the incident, explaining that she and her friends had front row seats at the concert.

"He kept telling me to stop. He kept telling me to like calm down and not to dance," she recalled of the moment. "And I guess she noticed and she yelled at him and told him to leave me alone and that I wasn't doing anything wrong."

The next leg of Swift's tour will be at Gillette Stadium in Foxborough, Massachusetts.