A masked trio pummeled a cyclist in the head before stealing her backpack inside Central Park late Sunday — and the brave New Yorker fought off the muggers with her metal water bottle.

The violent strangers launched their attack around 9:45 p.m as Katherine Marroquin, 32, of the Bronx, biked through the iconic greenspace on her way home from her Upper West Side maintenance worker job — her routine for the past year because she feared taking the train.

Marroquin stopped to pick up her AirPods she’d dropped along the running path at East 90th Street and the East Drive when the masked menaces cornered her, demanded everything she had and repeatedly hit her on the head, she said.

“I grabbed myself to the bike and I covered my head because they were hitting me hard,” she said.

The goons snatched her phone from the front of her bike and tossed it into the lake, Marroquin recalled.

With Marroquin still on the bike and wearing a backpack, the trio grabbed her by the bag and started to tear through her belongings while continuing to hit and kick her, she said.

In a twist of fate that spared Marroquin from more serious injury, her Stanley water tumbler fell out of her bag, she said.

“When I saw the cup, the first thing I did was like, ‘Well, they’re gonna kill me,’ so I grabbed the cup and I just randomly hit everywhere,” Marroquin said.

All three attackers — who had not been caught by Monday — then fled on foot toward Fifth Avenue, police said. Cops believe all three suspects to be in their early twenties.

Despite losing her phone, her wallet that held $80, credit cards and Beats headphones, Marroquin said her use of the metal tumbler was the only reason the vicious crew didn’t “steal everything.”

“I am thankful that I am OK,” she said, adding that some victims of similar crimes “get hit in the head and never wake up.”

Although Marroquin was bruised and battered, she declined medical attention when police arrived at the scene.

“I just wanted to get home because my mom was worried, everybody was worried,” she said.

She said she woke up with several purple marks to her face and hands Monday.

“Everything is hurting, I’m sore everywhere,” she said.

Despite her pain and an offer from her boss to take the day off, Marroquin was back at work Monday.

“I’m still going to bike,” Marroquin said. “I feel like I’m not safe on the train either. That’s one of the reasons I stopped taking the train.”

The born-and-raised New Yorker said she has been biking for a year to avoid what she deems as an unsafe train ride from Manhattan to the Bronx.

“This was always a safe place,” she said, adding that she thinks the city needs to take a tougher approach towards criminals.

“I feel like they deserve consequences, not just, ‘Oh yeah, one ticket and that’s it.’ Then they’re gonna keep doing it again.”