The model and former wife of the actor has insisted that she was with him when he allegedly sexually assaulted a 16-year-old girl in 1986.
According to Neilsen, the alleged attack could not have taken place as she had spent every evening with Stallone back in 1986.
“During the summer of 1986 we were newlyweds. I was inseparable with Sylvester when 'Over the Top' was being shot in Las Vegas,” she told TMZ.
“The story claims that at approximately 8:30 in the evening during the shoot of the movie the person claims she was in our suite at the Hilton Hotel.
“This incident did not occur. Most of the day, I would watch him film, then we'd have dinner and go to our room. No other person was in the room with him, but me.”
Stallone has denied allegations that he sexually assaulted a 16-year-old fan in Las Vegas in the 1980s.
His spokeswoman described the story as “ridiculous” and “categorically false” after reports emerged in several publications.
The girl allegedly claimed the Rocky actor said he would "beat her head in" if she told anyone about the incident in a hotel room.
She told police she was left "humiliated and ashamed" and said she did not want to press charges so the case was dropped, the reports state.
An officer's report said the girl alleged they met in July 1986 in what was then the Las Vegas Hilton Hotel when she got an autograph from Stallone, then 40.
She claimed a bodyguard gave her keys to a hotel room where she later had sexual intercourse with both men on July 26, according to the report.