A 26-year-old straphanger was stabbed in the face by an unhinged stranger at a Brooklyn subway station Sunday evening, leaving him with a gaping wound that required 20 stitches.

The victim, identified as Mamadou Lo, was hopping on a southbound C train at the Fulton Street and Rockaway Avenue station at 5:55 p.m. when he was attacked, police said Monday.

Terrifyingly, Lo said his attacker wasn’t acting out of the ordinary before he suddenly turned violent.

Police did not reveal a possible motive for the attack and said an investigation into the incident is ongoing.

“I was literally just putting away my headphones, not paying too much attention,” Lo, a Manhattan kitchen manager, told The Post Monday. “Some guy is like walking – not fast or in any kind of aggressive manner that I would notice.

“As soon as I got up to him, it felt like he threw a sucker punch at me,” Lo added. “I guess he had some kind of metal object, a knife or something, and he stuck it under my chin.”

The wounded man was taken to Brookdale Hospital Medical Center, where he needed 20 stitches to close the gash on the left side of his face.

His attacker fled the station and remained at large later Monday.

“Inevitably I have to take the subway,” Lo said. “That’s how the majority of us New Yorkers live. Is there definitely some paranoia playing in my mind? A little bit, for sure.

“The actual injury itself and the recovery is one thing, and that’s more manageable,” he added. “But it’s also the mental distress that comes with it. Now it’s like, I have to look over my shoulder all the time, and I have to walk past the same spot where I got hit up. I’m always gonna be cautious and worried.”

The kitchen manager said he believes the city needs to do more to help troubled people like his attacker.

Police did not reveal a possible motive for the attack and said an investigation into the incident is ongoing.

Transit crimes in the Big Apple so far this year are on par with last year’s number over the same span, but the week ending Sept. 13 saw a 31% spike compared to 2025, NYPD stats show.

Sources: NY Post