Annie Farmer, who has been outspoken about the alleged abuse, used her true identity on the stand. The three prior victims who testified used pseudonyms or first names to protect their privacy.
Farmer said she was 16 when she visited the late financier and Maxwell, now 59, at his sprawling New Mexico ranch in 1996. Her older sister, Maria, worked for Epstein at the time in New York.
Maxwell offered to give Farmer a massage, and she agreed and got undressed, she told jurors. During the rubdown, Maxwell allegedly fondled her breasts.
"Once she pulled down the sheet, I felt kind of frozen," Farmer testified. Later on during the trip, Epstein crawled into her bed in the guestroom where she was sleeping.
"Suddenly Epstein kind of opened my door, bounding into the room in a playful way, saying that he wanted to cuddle," Farmer recalled. Then he "pressed his body into me," she said.
She excused herself to use the bathroom to get away from the convicted pedophile who was more than twice her age at the time.
A month later, Epstein and Maxwell allegedly sexually assaulted her older sister, Maria, at the Ohio compound of Les Wexner, former Victoria's Secret CEO, according to civil filings.
Epstein hanged himself in a Manhattan jail cell in 2019 while awaiting trial on federal sex crimes charges. He was 66 at the time.
Farmer's testimony was originally expected on Thursday but an attorney in the case fell ill and court was postponed. Prosecutors are expected to rest their case as early as Friday.
Maxwell, who has been jailed since her arrest, is accused of recruiting and grooming girls to be abused by Epstein from 1994 to 2004.
She's charged with six counts stemming from the alleged abuse of four victims, including sex trafficking of a minor and enticement of a minor. If convicted, she faces up to 70 years in prison.
She has denied the allegations.
The Associated Press and Reuters contributed to this report.