FORT BRAGG, N.C. — Defense lawyers for an Army general facing sexual assault charges say his accuser’s testimony gave them plenty to challenge as they prepare to cross-examine her on Monday.

The Army captain at the center of the closely watched case testified Friday that Brig. Gen. Jeffrey A. Sinclair twice forced her to perform oral sex on him during their three-year, illicit affair. The woman said the assaults took place in Afghanistan in late 2011 as she grew increasingly despondent over their adulterous relationship.

Sinclair, the 51-year-old former deputy commander of the storied 82nd Airborne Division, is believed to be the highest-ranking U.S. military officer ever court-martialed on sexual assault charges. He could get life in prison if found guilty.

Sinclair pleaded guilty Thursday to adultery and other charges that could send him to prison for up to 15 years. His lawyers are hoping the plea will limit some of the salacious evidence and reduce the case to his word against hers.

Defense lawyers will likely ask the woman about some of the thousands of text messages she exchanged with the general, many of them sexually explicit.

Four months after she claims Sinclair sexually assaulted her, records show the captain traded a series of affectionate e-mails with the general. The captain signed off by saying she “owed” him, a code word defense lawyers say the paramours used as a substitute for “love.”

The trial is unfolding with the Pentagon under heavy pressure to confront what it has called an epidemic of rape and other sexual misconduct in the ranks. On Thursday, the Senate rejected a bill that would have stripped commanders of authority to decide whether to prosecute serious crimes.

Sinclair’s accuser testified that the first assault took place in her office in Kandahar when she told him how she hated her life, hated working for him and believed the general was just using her for sex.

She said the second assault took place in his office days later after she asked him to move her to another job. She said that after that episode, they never had sex again.