An attorney for Taylor Swift told jurors Tuesday that his superstar client is "absolutely certain" she was sexually assaulted and will prove it in court during the civil trial of dueling lawsuits filed by Swift and a former radio host.

In his opening statement, lawyer Douglas Baldridge asked what possible reason Swift would have to make up an allegation that former Denver radio host David Mueller touched her backside during a concert meet-and-greet in 2013.

"That's the one and only story we have to tell you — that Mr. Mueller grabbed her rear end," Baldridge said.

The case went to court after Mueller sued Swift, claiming her false accusation cost him his job at a country music station. He is seeking at least $3 million in damages.

Swift countersued, claiming sexual assault.

Earlier in the day, an attorney for Mueller told jurors that inappropriate touching is wrong, but falsely accusing someone of the offense is equally unacceptable.

"Let's be clear about something from the onset — inappropriate touching is offensive, it's wrong and should never be tolerated," Attorney Gabriel McFarland said in his opening statement.

"Let's also be clear that falsely accusing someone of inappropriate touching is equally offensive, it's wrong and should not be tolerated," he said.

Baldridge emphasized the age difference between Mueller, then 51, and Swift, then 23. He also said it was an assault, not inappropriate touching.

Swift and Mueller are both expected to testify in the case, along with Mueller's former boss and members of Swift's entourage.

Among the evidence in the case is a photograph obtained by TMZ but sealed by the court that shows Mueller with his hand behind Swift, just below her waist, at the pre-concert event.

Swift and Mueller are both smiling in the picture.

Her lawyers have called the photo "damning" proof that Mueller groped her.

Mueller says the photo only shows him trying to jump into the frame.

Potential jurors were asked whether they or relatives had ever been inappropriately touched or wrongfully accused of groping someone; and whether they were fans of Swift.

One man who ultimately was not selected told U.S. District Judge William Martinez that he was not necessarily a fan, "but her music is catchy and it's good vibes." The judge laughed and said, "very good."

The case is being heard in federal court because Swift and Mueller live in different states — Swift in Nashville, Tennessee, Mueller in Colorado — and damages at stake exceed $75,000.

The trial is expected to last about two weeks.

Swift is seeking a verdict that awards her $1 to hold Mueller responsible and serve "as an example to other women who may resist publicly reliving similar outrageous and humiliating acts," her lawsuit says.

About a dozen fans lined up outside the courthouse, including three high school students who showed up before dawn, for a pass allowing them inside to watch the civil trial.

"I love how she's suing him for $1 because she doesn't need the money but she wants to make it a point that women don't need to take this," said Vega Zaringlee, 12.

Associated Press writers James Anderson and P. Solomon Banda contributed to this report.