The lawsuit, which was filed Monday night and appeared on the Harris County District Clerk's website Tuesday morning, alleges that Watson "assaulted and harassed Plaintiff by exposing himself to her and touching her with his penis."
The incident allegedly took place in California, just the second of the 14 allegations to take place outside the Houston area.
The traveling massage therapist alleges that when she arrived at the address Watson gave her, he led her to a room and "locked the doors behind him." After Watson allegedly "forced Plaintiff's hand onto his penis" during the massage, he allegedly told her, "I will not have you sign a NDA but don't ever talk about this."
The plaintiff also alleges that Watson reached out on Instagram in December "acting as if nothing had happened."
Watson has denied wrongdoing, and his attorney Rusty Hardin said Friday that the allegations against the quarterback are "meritless."
"I have never treated any woman with anything other than the utmost respect," Watson said in a statement he posted on Twitter on March 16.
Tony Buzbee, the attorney for the plaintiffs, said in an Instagram post on Saturday that he would submit affidavits and evidence from several women to the Houston Police Department and the Houston district attorney Monday morning. He also said he will request that a grand jury consider the evidence and determine whether charges should be brought against Watson by the state of Texas.
Dane Schiller, a spokesperson for the Harris County district attorney, said Monday that it would be "inappropriate" for the DA's office to comment on the lawsuits against Watson.
"It would be inappropriate for the District Attorney's Office to comment on a civil lawsuit, and we refrain from publicly discussing allegations in any matter until and if a criminal charge is filed; we do this out of fairness to all," Schiller said in a statement.
Last week, NFL spokesperson Brian McCarthy said "the matter is under review" pertaining to the league's personal conduct policy, and the Texans said in a statement that they would stay in close contact with the NFL during its investigation.
"I fully support Deshaun," Fuller told reporters. "I don't know any of the specifics about what's going on with him, but I fully support him. I've been talking to him. To me, it seems like his head is on completely straight. I'm just looking forward to seeing where everything goes. Hopefully he's OK."
ESPN's Cameron Wolfe contributed to this report.