A fearless pit-bull puppy out for a walk with his owner’s girlfriend sank his teeth into a creep who attacked the teen — and drove the pervert back into the night.

“He’s a good boy. I think he saved my life,” Maya Fairweather, 18, told The Post of spunky Apollo, the 5-month-old pooch who saved her Monday evening in Brooklyn.

Fairweather was at the apartment of her boyfriend, Carlos Guzman, and decided at around 10 p.m. to take his playful new puppy for a walk in the Red Hook Recreation Area park.

She put her headphones on and let her four-legged friend off the leash so he could romp in the park for a while.

“I felt someone pull my headphones,” she recalled. “I thought it was my boyfriend grabbing me, so I turned around and smiled — but it wasn’t my boyfriend.”

It was a strange man, who seized her by the jacket and pushed her to the ground. He tried to pull off her pants.

“I fell down on my hands,” Fairweather said. “I just closed my eyes because they say that if you see their face, they will kill you. I froze. I was really scared.”

Fairweather had kept the pup’s leash in her pocket, so she figures the fiend probably did not realize she was protected — by a fearsome guard-puppy.

“Apollo helped me; he came and bit him in the leg,” she said

The pit bull chomped so hard that the man had to struggle to shake him off.

“I heard him say, ‘F–k!’ and I was able to run away. I ran across the street,” Fairweather said.

The dog finally relented and the attacker darted away.

“He was protective,” Fairweather said of her furry hero. “I think it would’ve been a lot worse. I wouldn’t have been so lucky.

“He is a sweet dog. I never thought he would bite anyone. He never bit anyone before. He’s usually very friendly and just jumps on everyone.”

As for her attacker, Fairweather had this to say: “I just hope he bit the s–t out of you.”

Fairweather ran back to the apartment, where her boyfriend’s sister, Destiny Guzman, 20, took her to the local police station house.

Law-enforcement sources said cops are searching for the attacker.

“I wasn’t there, but I know that that dog saved her life,” Destiny Guzman told The Post. “If it wasn’t for that dog, things would be a lot worse. [Fairweather is] tiny.”

Carlos Guzman’s mother, Sonia Valcarcel, said she initially did not want to have a dog — but now, Apollo is winning her over.

“I really never wanted that dog. But you have to give him credit,” the mom admitted.

“The dog is a hero, he protected her. I’m sad she had to go through that, but at least, because of the dog, she was able to escape.”