Floyd Mayweather Jr reportedly has $100 bills placed in his custom-made mouthguards.
The 38-year-old, who is nicknamed 'Money', is preparing for the highly-anticipated bout with Manny Pacquiao in Las Vegas on May 2.
According to TMZ, the American, who is never shy about showing off his wealth, pays around $25,000 (£16,740) to have $100 bills stuffed into the guards that protect his teeth during fights.
Mayweather, who uses the service of New York-based dentist Dr. Lee Gause, also reportedly has mouthguards that include diamonds and gold flakes.