Pittsburgh Pirates pitcher Felipe Vazquez admitted he had “sex but not really” with a 13-year-old girl, according to a criminal complaint released Wednesday.

The new court papers describe the lefty All-Star’s illegal relationship with the teen — including the alleged assault in August 2017 — in disturbing detail.

Vazquez, 28, told investigators he drove his red Ford Mustang roughly an hour from Pittsburgh to the girl’s home in Scottsdale, Pennsylvania, and that the two began fooling around in her driveway.

He described the victim as “already being ready” for sex and then admitted they had “sexual intercourse inside of his vehicle,” the complaint said.

The Venezuela-born Vazquez — whose nickname is “Nightmare” — described the encounter as “sex but not really” because it was cut short.

The filing also alleges that the athlete sent the victim an X-rated text message as recently as July, saying he wanted to “finish” the deed.

Vazquez is charged with felony counts of statutory sexual assault, unlawful contact with a minor, corruption of minors, as well as a misdemeanor count of indecent assault of a person less than 16 years old.

He also faces solicitation of a child and providing obscene material to minors out of Florida for allegedly sending the girl a video of himself in a sex act.

The two also allegedly exchanged nude photos and the victim sent him videos in which she performed sex acts on herself, according to court papers.

When police interviewed him at his home in Pittsburgh’s Strip District on Tuesday, Vazquez claimed he couldn’t remember the girl’s name but then said he knew her after he was shown her photo.

“Vazquez recalled the Victim sending him a message once on Instagram but claimed initially that he refused to communicate with her due to her age,” the complaint said.

He also told police that the victim “looked too young and that she appeared to be 16 years of age or younger.”

At a press conference Wednesday, Pennsylvania State Trooper Steve Limani called the allegations “horrific and appalling and disgusting.”

“It’s a shame. It’s sad,” he told reporters. “It’s disgusting every time I have to come up here in my 21-year career and talk about something of this nature.”

Limani said police believe there was only “one physical interaction” between the two.

The girl’s mother allegedly found the illicit photos and texts and notified police in Florida. When they interviewed the girl, she told them about the incident in Scottsdale — launching the investigation by Pennsylvania authorities.

Limani said authorities in Pennsylvania will get the first crack at prosecuting Vazquez before he’s extradited to the Sunshine State.