US boxing superstar Floyd "Money" Mayweather fights undefeated Japanese kickboxing prodigy Tenshin Nasukawa on Monday, a New Year's Eve multi-million-dollar rumble outside Tokyo to be held under boxing rules.
At 41, Mayweather is more than twice the age of his Japanese opponent, the 20-year-old known as "Ninja Boy" but will carry a more than 4kg (9lb) weight advantage into the ring.