Cleveland Cavs player Kevin Porter Jr. allegedly punched a woman in the face and ripped off her wig during an altercation back in August ... but Porter's attorney says the claim is bogus.
The allegations are spelled out in police reports obtained by TMZ Sports ... which detail an August 16 incident involving Porter, his sister and two other women.
The 2 alleged victims told police things popped off when "words were exchanged" at an apartment complex in Downtown Cleveland ... and things escalated from there
One of the alleged victims told cops Porter's sister struck first -- punching one of the women in the face.
That's when, the women say, Kevin jumped in ...
"At this time, Mr. Porter threw his drink in the face of [an alleged victim] and then ripped the wig off her head and then punched her in the left side of her face causing slight swelling visible at the time of this report," the police report says.
Cops say they spoke with a witness who saw the whole incident and backed up the two women ... claiming the Porters were the aggressors.
In fact, the witness says she saw Kevin Porter with one of the women's "weave in his hand when he then punched [one of the women] in the face causing her to [fall] into the refrigerator."
When cops arrived, they noted both of the women who allegedly fought with the Porters had visible injuries.
The woman who was allegedly struck by the NBA player had a swollen left cheek, cops say. The other woman had a broken fingernail and a small lump on her forehead.
Both women opted to NOT receive medical treatment at the time of the incident.
Cops say they told the two women to contact the city prosecutor's office if they wanted to press charges. So far, neither Porter nor his sister have been charged with a crime.
Porter's attorney, Alex Spiro, issued a statement adamantly denying the allegations -- saying, "There is no truth to this allegation which is why the allegation has led nowhere."
20-year-old Porter has other legal issues ... he was arrested Sunday following an early morning crash in Ohio.
After the wreck, cops say they found a loaded handgun and what appeared to be weed inside the vehicle. He is facing multiple charges including felony improper handling of a firearm inside a motor vehicle and misdemeanor 1st-degree drug abuse -- along with other traffic citations.
Porter pled not guilty to the misdemeanor charges -- and entered a no plea on the felony.
We reached out to the Cavs for comment -- so far, no word back.