Jordan Johnson's attorney responded that the woman wanted a relationship with the "star quarterback," then made false accusations when one did not develop after the two had consensual sex.
Johnson, 20, is accused of assaulting the woman as they watched a movie together at her home last year. The trial began amid continuing NCAA and federal investigations into how the school and the city of Missoula respond to rape allegations on campus.
Prosecutor Adam Duerk told the jury the woman tried to stop Johnson after they began kissing in her bedroom, but he forced himself on her.
"This case is about a young woman who was horribly betrayed," Duerk said.
Johnson's attorney, Kirstin Pabst, made reference in her opening statement to comments by former U.S. Rep. Pat Williams on the eve of the trial that the university's recruiting system let "thugs" into the program.
Johnson is no thug—nor did he rape his accuser, Pabst said.
The woman "wanted to have a relationship with the star quarterback. That's why she gave him sex. But the fact that he did not give her a relationship does not make what happened a crime," Pabst said.
Williams, a member of the Board of Regents that oversees the university system, has said he was not referring to Johnson.
Jury selection took a day and a half and involved screening more than 150 potential candidates. The final panel features seven women, five men and five alternate jurors.
The two sides made their opening statements, and then the alleged victim took the stand.
Under questioning, she told the jury about her background and how she and Johnson became acquainted. She said she was attracted to him, they had gone on dates and kissed, but then fell out of touch for a while until the weeks before she invited him to watch a movie at her home on Feb. 4, 2012.
She said she wasn't planning to have sex with him that night. Before she could testify about what happened, the proceedings ended for the day.
Her testimony is expected to continue Wednesday.
An outside investigator was hired by the university in December 2011 after two students reported being drugged and raped.
The investigator found nine alleged rapes or sexual assaults involving students had occurred between September 2010 and December 2011, including at least two that hadn't been reported.
Two more allegations were made after the investigator's report, including the claim against Johnson, which surfaced in March 2012 when the woman obtained a temporary restraining order against him.
Johnson led Montana to the Football Championship Subdivision semifinals as the 2011 starting quarterback.
In a separate case, former Montana football player Beau Donaldson pleaded guilty to rape and was sentenced to 10 years in prison.
The university received a grant from the DOJ Office of Violence Against Women that provides it with training in mandatory education for students and for disciplinary boards, community response teams and campus law enforcement, spokeswoman Peggy Kuhr has said.