A man took a punch to the face after declining to swipe another man through a turnstile in Brooklyn.

Cops said the victim was left bruised Oct. 19 at around 5 a.m. after he stepped into the Eighth Avenue subway station in Sunset Park.

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The straphanger didn't even make it to the N train platform before coming across the suspect who investigators said asked that victim to swipe him through with his MetroCard.

The rider tried to avoid the suspect by approaching a different turnstile when the suspect approached the man he just asked for a favor.

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That's when the attacker suddenly punched the rider's face and then ran out of the station to unknown parts.

The victim refused medical attention at the scene, but police want to track his assailant down.

The NYPD described the suspect as a black man with a dark complexion in his 30s, possibly around 6-feet-2-inches tall and weighing about 180 pounds. He was last seen with long dreadlocks while wearing a gray jacket and dark pants.

Cops ask that anyone with information in about the suspect or punch anonymously call the NYPD's Crime Stoppers Hotline at 800-577-TIPS or text their tips to 274637 (CRIMES) then enter TIP577.