DENVER (Reuters) – Taylor Swift might turn up in a federal court in Denver on Monday as lawyers for the pop star and a Colorado radio personality start jury selection for dueling lawsuits over whether the former disc jockey groped her four years ago during a photo shoot.

Swift, 27, is expected to take the witness stand during the trial in U.S. District Court to testify about the incident, which resulted in broadcaster David Mueller’s firing from Colorado music station KYGO-FM.

The bitter litigation centers on Swift’s allegations that Mueller slipped his hand under her dress and grabbed her bare bottom as they posed together during a meet-and-greet session before her June 2, 2013, concert in Denver.

“It was not an accident, it was completely intentional, and I have never been so sure of anything in my life,” Swift said in describing the incident during a deposition.

Mueller, 55, sued first, claiming the singer-songwriter had falsely accused him of the groping and pressured station management to oust him from his $150,000-per-year job at the station, according to the lawsuit.

Swift countersued for assault and battery, and that became part of the same trial.

Mueller denies that anything inappropriate occurred during the brief backstage encounter in which he stood on one side of the pop star and his girlfriend on the other.

“The contention that Mr. Mueller lifted up Ms. Swift’s skirt and grabbed her bottom, while standing with his girlfriend, in front of Ms. Swift’s photographer and (her) highly trained security personnel … is nonsense,” the lawsuit said.

Mueller is suing under tort claims of interference with contractual obligations and prospective business relations. Jurors will determine what monetary damages, if any, he is entitled to if Swift is found liable.

In court filings, Swift said while her manager informed KYGO management about the incident, she did not demand that Mueller be fired.

The radio station conducted its own investigation, and two days after the incident fired Mueller for violating the morality clause of his contract, court documents show.

The judge has placed a gag order on all parties, and attorneys for both sides did not respond to messages seeking comment.

Swift, one of the most successful contemporary music artists, earned $170 million between June 2015 and June 2016 following a world tour and her best-selling “1989” album, according to Forbes Magazine.