Floyd Mayweather Jr's father fears that the pound-for-pound king will "go broke", despite being one of the highest-paid athletes in the world.
The 38-year-old is expected to earn upwards of £130m for his highly-anticipated showdown against Manny Pacquiao this weekend.
The American boxer constantly flaunts his wealth on social media, and Mayweather Sr, who works as the sportsman's trainer, is concerned that his son's extravagant spending could wreck his future.
"Look at all the millionaires who go broke," the Daily Mail quotes Mayweather Sr as saying. "When you have this much money sometimes you can't control it.
"Another hundred million, two hundred million on top of what you already have looks like a tall thing, but you can do all kind of things with money.
"If Floyd does the right thing with his he will be alright for the rest of his life, but you can get through any amount in two years spending on possessions, trips, cars, women. Most fighters go down that hole."
Mayweather, who is expected to retire on 49 fights, will be aiming to extend his unbeaten run to 48 when he faces Pacquiao at the MGM Grand Garden Arena in Las Vegas on Saturday.
