By TMZ Sports

Veteran trainer and former fighter Floyd Mayweather Sr. has turned himself to answer claims that he attacked a woman on the night of last September's showdown between Canelo Alvarez and Gennady Golovkin at T-Mobile Arena.

The woman decided to press charges. Officials eventually charged Floyd with misdemeanor battery and on January 16, a warrant was issued for his arrest, according to court records.

On Thursday, Sr.'s attorney appeared before a Vegas judge ... and pled not guilty on Mayweather's behalf. As we previously reported, Mayweather Sr.'s rep told us he's totally innocent ... and never laid a hand on the alleged victim.

Mayweather Sr. is due back in court on March 27.

As previously reported, the alleged victim was heading toward Floyd's car when an argument broke out between the two. Floyd allegedly told the woman to get out of the car, but she refused so he reached in and dragged her out by the leg.

The 65-year-old Floyd allegedly made things worse by punching her in the leg once she was out of the car. The accuser claims Floyd then got in the driver's seat and sped off without her.

The woman was hospitalized for minor injuries.

We spoke with Floyd's rep who tells us the alleged victim is "trying to extort money and she's angry because she's not getting the money from Floyd. It's not going the way she wants it to go."

Mayweather Sr. is best known as being the father and trainer of five division world champion Floyd Mayweather Jr., who retired from the sport last August after stopping UFC superstar Conor McGregor in the tenth round, also at the T-Mobile.

He also trained several other fighters over the years, including six division world champion Oscar De La Hoya, cruiserweight Andrew Tabiti, UK legend Ricky Hatton, former champion Chad Dawson and numerous others. He currently trains a stable of fighters, including undefeated rising prospect Devon Haney.