Pop music superstar Taylor Swift has taken the stand in a sexual assault suit against the DJ she claims grabbed her backside at a meet-and-greet with fans.

Ms Swift claims David Mueller, a DJ for radio station KYGO-FM, grabbed her buttocks from under her skirt while the two were posing for a picture in 2013. A member of the singer’s security detail later confronted Mr Mueller about the incident, and Ms Swift filed a complaint with the radio station.

Testifying on Wednesday, Ms Swift refused to criticise her bodyguards for not responding sooner. Instead, she told Mr Mueller's lawyer: “I’m critical of your client sticking his hand under my skirt and grabbing my a**."

The incident, she added, “was horrifying, shocking, and we had never experienced it before”. (The massively popular American singer said she thought she’d experienced “every awkward encounter” before this.)

The legal back-and-forth was initiated by Mr Mueller, 55, who claims he lost his job after Ms Swift reported him to the radio station. KYGO Vice President Robert Call confirmed on Wednesday that he had fired the DJ “for touching Taylor’s rear end”.

Mr Mueller sued the singer for ruining his radio career, claiming she had fabricated her claims and that he made no inappropriate contact with the her at the event.

Ms Swift counter-sued for assault and battery, requesting symbolic damages of $1.

Mr Mueller’s attorney, Gabriel MacFarland, said the singer's allegation of misconduct "was careless, it was reckless and it was part of in many ways what has destroyed Mr. Mueller's life”.

Ms Swift, meanwhile, described the incident as an “intentional” and “very long” grab for her buttocks. She claims her photographer witnessed the incident and took a picture of it. Her legal team has submitted the photo for evidence.

The singer says she continued the meet-and-greet after the alleged assault because she did not want to disappoint her fans. When Mr McFarland suggested she could have taken a break, Ms Swift responded that Mr Mueller “could have taken a normal photo with me”.

From beef to BFFs to beef again: Kanye West and Taylor Swift Show all 6 1 /6 From beef to BFFs to beef again: Kanye West and Taylor Swift From beef to BFFs to beef again: Kanye West and Taylor Swift September 2009 NEW YORK - SEPTEMBER 13: Kanye West (L) jumps onstage after Taylor Swift (C) won the "Best Female Video" award during the 2009 MTV Video Music Awards at Radio City Music Hall on September 13, 2009 in New York City. (Photo by Christopher Polk/Getty Images) From beef to BFFs to beef again: Kanye West and Taylor Swift September 2009 NEW YORK - SEPTEMBER 13: Kanye West (L) jumps onstage after Taylor Swift (C) won the "Best Female Video" award during the 2009 MTV Video Music Awards at Radio City Music Hall on September 13, 2009 in New York City. (Photo by Christopher Polk/Getty Images) Christopher Polk/Getty From beef to BFFs to beef again: Kanye West and Taylor Swift February 2015 LOS ANGELES, CA - FEBRUARY 08: (L-R) Recording Artists Taylor Swift, Jay Z and Kanye West and tv personality Kim Kardashian attend The 57th Annual GRAMMY Awards at the STAPLES Center on February 8, 2015 in Los Angeles, California. (Photo by Larry Busacca/Getty Images for NARAS) From beef to BFFs to beef again: Kanye West and Taylor Swift August 2015 LOS ANGELES, CA - AUGUST 30: Recording artist Kanye West (L) accepts the Video Vanguard Award from recording artist Taylor Swift onstage during the 2015 MTV Video Music Awards at Microsoft Theater on August 30, 2015 in Los Angeles, California. (Photo by Kevork Djansezian/Getty Images) From beef to BFFs to beef again: Kanye West and Taylor Swift April 2016 Kanye West drops 'Famous', which includes the controversial line 'I feel like me and Taylor might still have sex/Why? I made that bitch famous' From beef to BFFs to beef again: Kanye West and Taylor Swift July 2016 Kim Kardashian releases of audio of Tayior Swift approving the lyrics to 'Famous' Getty

Reporters in the courtroom described the 27-year-old singer as frustrated but prepared, sitting at the stand with her hands clasped and hair back.

“I am not going to allow your my client to make me feel like it is anyway my fault, because it isn’t,” she told Mr Mueller’s attorney at one point.

She was dismissed after less than an hour on the stand.

Ms Swift’s mother, Andrea Swift, also testified on Wednesday. The elder Ms Swift said she "wanted to vomit" after her daughter told her about the alleged assault. She did not seek out eyewitness testimony, she said, because she had no reason to doubt her daughter’s claims.

Pointing to Mr Mueller in the courtroom, she said: "He sexually assaulted my daughter, right there, that guy.”