An eight-count criminal complaint filed Thursday by Clark County District Attorney David Roger significantly raised the ante in the criminal case accusing Mayweather of hitting his ex-girlfriend, threatening their children and taking cell phones during an argument at the woman's home a week ago.
Mayweather previously faced one grand larceny charge carrying a possible sentence of five years.
The new complaint adds two coercion and one robbery charge, plus a domestic battery and three harassment charges.
It increases to 34 years the possible penalty the 33-year-old Mayweather could face if convicted of all charges.
He's due for arraignment Nov. 9 in a Las Vegas court.
Mayweather's lawyer, Richard Wright, hadn't seen the new complaint. He's declining immediate comment.
Mayweather is undefeated as a professional fighter and is considered one of the sport's top performers, with a record of 41-0 and 25 knockouts. He goes by the nickname "Money" and earned more than $20 million in May from his fight in Las Vegas against "Sugar" Shane Mosley.
Mayweather has also been arrested several times over the years on battery and assault allegations.